How many categories of intelligence are mentioned in the passage

A．Because everyone have the same chance in this way.
B．Because the IQ is an average and doesn't say any thing about special abilities.
C．Because they are the only three types of questions that can be used at present.
D．Both A and B.

A．anyone without breakfast does improve his performance
B．not giving people breakfast improves performance
C．having breakfast does not improve performance, either
D．people having breakfast do improve their performance, too