African cheetahs, which suffered a dramatic drop in population, rebounded in number to create a population of
unusually similar genetic animals. This is called

A) a bottleneck
B) genetic equilibrium
C) speciation
D) the founder effect

Ihave no idea how to solve these. plus there's another question that is 2) a 10 kilogram meteorite is collected in space and brought back to earth. it is composed of 1.25 kg of uranium-238 and 8.75 kg of lead-206. how many u-238 half lives have passed? what is the approximate age of the meteorite?