Answer:
I'm pretty sure its genetic drift
The hind legs of the frog are adapted for leaping and swimming. They have strong extensor muscles. When these muscles contract, the limbs extend thrusting the foot against the water or land. The frog's forelimbs are shorter and used to steer the frog while swimming and to absorb shock while landing.
If you by any chance cook something with a bone in it (like a thick chicken bone). Put it in vinegar for a few days and the acetic acid will essentially remove the calcium out of the bone and make it wiggle and jiggle and not be hard like a bone anymore. The longer you leave it the more it will wiggle!
Survival of the fittest. The strongest offspring will survive to adulthood and reproduce - their offspring will have stronger genes than prior generations. The weaker offspring will not live to adulthood and not produce offspring, therefore the weaker traits will die out with each generation
Answer: c humans would find more efficient ways of growing crops
Explanation: