Have* this is because has* is past tense and have is more appropriate since there are multiple things you are referring too (Mercury, Venus, Earth and Mars). To be honest, these planets have a molten core.
I'm thinking C it fits the most.
The correct answer is option:
A. They are entirely aquatic, meaniing they spend their full lives in the waters.
Answer:
an institution of higher education offering courses at degree level or below, especially in vocational subjects.
