Which of the following artists led the pop art movement?A) Betty Friedan B) George Harrison C) Joan Baez D) Andy Warhol
The only possible answer to this question (of the options that you have given us) is D. None of the other people mentioned is or was a serious visual artist. Andy Warhol, by contrast, was a famous artist who was very important in the pop art movement of the 1950s and beyond. He was perhaps most famous for his paintings of Campbell's Soup cans.
All of the other people mentioned were famous, but had nothing to do with visual arts. Friedan was a feminist writer. Harrison was a member of the Beatles. Baez was a folk singer. None of them was closely connected to pop art.