Final answer:
Conflicts over parental investment are most pronounced in birds, as they invest in long-term care for a fewer number of offspring, leading to greater significance for the survival of each chick and potential conflicts over resource allocation between parents and offspring.
Step-by-step explanation:
One would expect that conflicts between parents and offspring over parental investment would be the most pronounced in organisms that invest in long-term parental care. Considering that in most species of fish, amphibians, and reptiles, parents provide no care to their offspring, while birds and mammals are known for their parental care, the conflict is more likely to arise in these latter groups. Most often, bird and mammal mothers, and occasionally fathers, are involved in nurturing their young. This long-term care ensures a higher survival rate for a fewer number of offspring, which makes the parental investment considerably more significant when any given offspring is at risk. Therefore, the correct answer is D) birds, since they are associated with long-term parental care. Birds lay fewer eggs, which means each chick represents a significant portion of the parents' reproductive output, leading to a greater investment in each chick's survival. This level of investment can lead to conflicts between parents and offspring, as each chick may demand more resources than the parents can provide or want to provide, given their need to maintain their own health for future reproductive opportunities or to care for other offspring.