Heritability refers to the extent to which trait variations among individuals are attributable to their differing

Phenotypes

Explanation:

Heritability refers to the extent to which trait variations among individuals are attributable to their differing observable and most often definitive or measurable physical features, often called phenotypes. Examples of this variation could be something like height or eye colour. Basically it has to be traits that depend on genetics that environmental factors

answer: b

coz red blood cells marrow and circulates the body for 120 days.

d.embryo is the correct one