What is the key factor in evolutionary change,according to Darwin's theory of evolution

A)  interaction of heredity and the environment 
B)  genetic transmission of learned behaviour 
C)  relative success of aggressive predators 
D)  variations in reproductive success

According to Darwin's theory of evolution, the key factor in evolutionary change is variations in reproductive success. This means that individuals with traits that are better adapted to their environment are more likely to survive and reproduce, passing on their advantageous traits to their offspring. Over time, these advantageous traits will become more common in the population, leading to evolutionary change. The interaction of heredity and environment and genetic transmission of learned behavior may also play a role in evolution, but the most important factor is variations in reproductive success. The relative success of aggressive predators is not necessarily a driver of evolutionary change, as it depends on the specific environmental context.