Genetics alone cannot explain the rapid change in IQ across generations, so environment must be the explanation

During and after puberty:

boys become much stronger than girls. both genders become equally strong. girls become weaker than during elementary school. girls become thinner than during elementary school.

What could Watson and Rayner have done to eliminate Little Albert's conditioned fear?

a) show Albert a toy rat instead of a live one b) let Albert touch a Santa Claus beard repeatedly c) show Albert a rat many times without a loud noise following d) have Albert hear a loud noise many times without a rat present