Final answer:
The three common substances important in planet formation are gases (mainly hydrogen and helium), ices (like water, methane, and ammonia), and rocks (containing magnesium, silicon, iron, etc.). The correct option is B.
Step-by-step explanation:
The three "common" substances that are believed to be important in planet formation are: gases, ices, and rocks. Each of these materials plays a distinct role in the structure and composition of planets.
The term 'gases' primarily refers to hydrogen and helium, which are the most abundant elements in the universe.
'Ices' in this context are compounds formed from elements like oxygen, carbon, and nitrogen, which typically include water (H₂O), methane (CH₄), and ammonia (NH₃), but may also include carbon monoxide and dioxide among others.
'Rocks' encompass less abundant materials including elements like magnesium, silicon, and iron.
These substances provide insight into the processes that likely took place during the early stages of the solar system's evolution, where the inner planets formed with more of these heavier elements and the outer planets encapsulated more of the lighter gases and ices.The correct option is B.