In a village,some people have very few children and some people have a lot of children.According to Darwin,what varies among people in this village

A)  fertility
B)  heritability 
C)  fitness
D)  genotype

Fertility

The natural capability to produce offspring, often assessed through rates of conception and childbirth.

Heritability

A statistic used in genetics to estimate the proportion of variation in a phenotypic trait in a population that is attributable to genetic differences among individuals.

Fitness

Fitness refers to the condition of being physically fit and healthy, often resulting from regular physical activity and exercise.