Natural proteins most commonly contain linear polypeptides between 100 and 1000 residues in length. One of the reasons polypeptides outside this range may be disfavored is that

B) smaller polypeptides do not form stable folded structures.

clumped distribution, because you'de have all of the population gathered in a relatively small are.

it's the most common because it provides protection and a mate for reproduction

example: humans, seeweed, cattles, etc.

not necessarily. higher fitness requires the organism to be reproductive successful. for example, an organism at age 10 with 15 offspring is much more fit than an organism at age 15 with only 5 offspring.