What does a high heritability index indicate about a trait like intelligence?

A high heritability index indicates that a trait, such as intelligence, has a significant genetic contribution. This means that a considerable portion of the variation in intelligence among individuals within a population can be attributed to genetic differences. It suggests that genetic factors play a key role in determining an individual’s cognitive abilities, making this option correct.

It's important to note that a high heritability does not imply that the trait is solely determined by genetics, which is why the statement about it being solely determined by genetics is not accurate. Heritability does not mean that the environment has no effect; rather, it indicates the relative contribution of genetics compared to environmental factors in the expression of the trait. High heritability also does not imply a lack of potential for modification through experience, contradicting the assertion that such traits cannot be influenced by environmental changes or learning. Therefore, while genetic factors are crucial, they interact with environmental influences, contributing to the complexity of traits like intelligence.