A – Correct
The passage just assumes that high earner in sport and entertainment are not generally intelligent.
B – Wrong
The passage does not make a correlation between IQ and education. Therefore, this is wrong.
C – Wrong
The passage only states that the professions of parents was not considered.
D – Wrong
This is not necessarily true. The word ‘guarantees’ is too strong and besides, the passage focuses on the correlation between parental income and IQ whilst this statement only focuses on level of intelligence.