Because an organism with a genetic variation may have better chances of breeding and passing on that trait if the trait is beneficial to the survival of that organism. This leads to that trait being passed on and becoming wide-spread over generations of reproduction; natural selection.
The answer is a) because when muscles contract, myosin heads attach to actin and breaks down ATP. Energy is released, pulling actin filaments and muscle contracts. Essentially actin and myosin filaments are sliding past each other.
Survival of the fittest (which means those who have better adaptions for there environment will survive and spread on their genes while the lass well adapted ones will die off)
Answer:
I don't know much but try D srry I'm not good at it
