Why seven
Uranus, Neptune and Pluto are not here, and the omission is deliberate rather than an oversight. Astrology was worked out with the seven bodies visible to the naked eye, and every rulership, dignity and traditional judgement in the system is built from them. The outer three were discovered in 1781, 1846 and 1930, and their meanings were assigned afterwards.
That does not settle whether the modern additions are useful, an argument astrologers are still having. It does mean the seven have a coherence the ten do not: each one governs a distinct department of life, none of them overlaps much with another, and between them they cover most of what a person does in a week. That is what makes them sortable by questionnaire at all.
What each planet is responsible for
The short version, since the result will assume you know it. The Sun is purpose and visibility, what a person is centrally trying to be. The Moon is the reflex underneath the decision: mood, habit, the thing you return to when nothing is required of you. Mercury handles thought, language and the carrying of information between people, and the tradition is careful to call it a messenger rather than an author.
Venus governs attraction, taste and settling matters without force. Mars is the opposite faculty, the appetite that cuts and competes and takes. Jupiter is scale and judgement, the search for the principle behind the facts. Saturn is limit and time, the discipline that makes a slow thing possible and the refusal that makes room for it.
What the questions are doing
Each option belongs to one planet by its department rather than by its mood. A question about an unattended group offers four workable answers: taking visible charge, settling who is unhappy, building a structure, or arguing for a direction. Those are the Sun, Venus, Saturn and Jupiter respectively, and none of them is the right answer.
That is the design constraint throughout. Where one option is obviously better, the question measures nothing except whether the reader can spot the flattering choice. The situations were picked so that four different people would each pick a different line and each be able to defend it.
The part worth keeping
The result is a game and the page says so. What is not a game is the vocabulary underneath it, which is the same one an astrologer uses when they say a chart has a difficult Saturn or a strong Venus.
Most people meet those terms as adjectives and never learn what they refer to. Having sorted your own answers against them, the words have something behind them, and a natal chart stops being a list of unfamiliar symbols. Your own placements are a separate matter, computed from a birth date, time and place, and are quite likely to disagree with the result here.
Questions people ask about this
Does this tell me which planet is strongest in my chart?
No. That is calculated from your birth date, time and place, and this page has none of them. The result reflects how you answered, nothing more.
Why are Uranus, Neptune and Pluto missing?
They were discovered long after the system was written, and the traditional structure of rulerships and dignities is built entirely from the seven visible bodies. Their meanings are a later addition and still disputed.
The Sun and the Moon are not planets.
Astronomically no, and astrology has always known it. In the older texts all seven are called the wandering stars, meaning the bodies that move against the fixed background, which is a description of what they do rather than what they are.
Can I get a result that contradicts my sun sign?
Easily, and it means nothing is wrong. Your sun sign describes where the Sun sat in the zodiac; this test sorts your answers by which planet's subject matter they fall under. They are different questions.
Is Saturn a bad result?
The tradition calls it the greater malefic and also credits it with everything durable. Structure, patience and the ability to refuse things are Saturn, and no long piece of work has ever been finished without them.
What should I do with the answer?
Read what the planet actually governs and then look at where it sits in your own chart. That is a real position, computed rather than guessed, and it is where the useful reading starts.