Why must there be variation in a population in order for natural selection to occur?

Which excerpt from the land, part 4 best supports the claim that paul is a talented horseback rider? a/“figure that says more than anything else! now, i want to ride that stallion! " b/my daddy shook his head. "paul only rides horses he knows. ” c/? i glanced over at the other rider. the fellow was older than i, and had the weight of a man on him. d/a man out of alabama, man name of ray sutcliffe, told my daddy i was such a good rider, he wanted me to ride some races for him.

Jason adds the antibiotic penicillin to a bacterial culture. the bacteria develop genetic modifications in their genome, which gives them resistance to the antibiotic penicillin. what caused this genetic modification?

Human genes only differ by less than percent. a. 1 b. 6 c. 11 d. 16