According to the theory of Darwinism, the survival of fittest individuals means

The correct option is D Maximum reproduction capacity
Charles Darwin has given the famous theory of Natural Selection. According to this theory, there is constant competition among different organisms to survive. They compete for their existence and to obtain the necessities of life. Among these organisms, nature selects the organisms that have the maximum capacity to adapt to their environment and survive the odds, which is known as the process of natural selection. Thus, nature selects the fittest of all organisms. This is known as survival of the fittest.

The organisms that have maximum reproductive capacity are said to be the fittest of all as they can extend their generation. So, option D "maximum reproductive capacity "is the correct answer.