Which Use of the Deviation IQ to Measure Intelligence Differences

Which use of the deviation IQ to measure intelligence differences is invalid?

A) to screen for scholastic aptitude for university students applying to medical school
B) to assess general cognitive functioning for young adults in the military
C) to study intelligence differences between 30-year-olds who are either self-made millionaires or bankruptcy filers
D) to study intelligence differences between young adults and senior citizens