I would say A is the correct answer. B and C are definitely wrong, and I think D is talking about genes and not chromosomes.
Orbital period is the <span> time taken for a given object to make one complete </span>orbit around another object. Mercury orbits the Sun in 88 days. Therefore, Mercury's orbital period is calculated by (88/365.25) or .241 Earth years. Hope this answers the question.
True vocal cords is the answer <span>ʕ•ᴥ•ʔ</span>
Gravity , Explosion
<u>Explanation:</u>
Nebulae are made of dust and gases—mostly hydrogen and helium. The dust and gases in a nebula are very spread out, but gravity can slowly begin to pull together clumps of dust and gas. As these clumps get bigger and bigger, their gravity gets stronger and stronger.
Eventually, the clump of dust and gas gets so big that it collapses from its own gravity. The collapse causes the material at the center of the cloud to heat up-and this hot core is the beginning of a star.
Climate, Land form/shape and fossils(he was most interested in this)