Astudy of adults aged 34 to 83 found that people high in fluid intelligence were exposed to stress and were likely to suffer from it.

The answer to the first unknown is "more stress" while in the second unknown is "less likely". Such as we have it as a study conducted for adults aged 34 to 83, it was found out that people high in fluid intelligence were exposed to MORE stress and were LESS likely to suffer from it.