Answer:
D. Selection has led to decreases in the size of fish at the age of reproductive maturity.
Explanation:
The larger body size of the fishes is not an adaptive trait as it reduces the survival chances of these fishes. The process of natural selection tends to increase the frequency of the traits that increase the survival fitness of the organisms. Here, the fishes with smaller body size at the reproductive age have greater chances of survival and would reproduce more to leave more progeny. Over the generations, the selection pressure would increase the proportion of fishes that are smaller during reproductive age.
Doesn’t normally happen until your 40’s or 50’s
