What occurred while the lunar surface was melted by radioactive heat ?

a) lava flows formed maria.
b) earth and a planetesimal collided.
c) the moon became geologically inactive.
d) bombardment by meteoroids formed the highlands.

lysosomes contain a variety of enzymes, enabling the cell to break down various biomolecules it engulfs, including peptides, nucleic acids, carbohydrates, and lipids (lysosomal lipase). the enzymes responsible for this hydrolysis require an acidic environment for optimal activity. hope i !

i believe the answer would be b. hope it : )