Most mammals during the mesozoic were
a. small and rodent-like
c. small and reptile-like
b. large and rodent-like
d. large and reptile-like

a. small and rodent-like

Explanation:

During the Mesozoic the first mammals appear, they lived with the dinosaurs and managed to survive the meteorite, the scientists explain that the underground burrows and the aquatic environments where the first mammals were hiding from the dinosaurs also managed to protect them from the rising temperatures, this  was thanks to theirs small size. According to paleontological studies it is known that the organization of mammals remained in the form of almost always insectivorous and small-sized animals, arboreal and nocturnal.

it would be heredity