Zelda was adopted when she was an infant. her adoptive parents' intelligence test scores are in the average range. her biological parents, on the other hand, have test scores that are well above average. when zelda is 30, what can be predicted about her performance on an intelligence test?

It can be predicted that  It will be more similar to her biological parents' test scores.
There are several factors that could influence someone's core intelligence, such as genetics, nutrition, and educational method.
But, the most important factor from all those three is the genetics. The parents will be much more likely to produce smart children if they're smart themselves.