According to social-role theory, today's gender differences exist because of

The answer is D) Social Pressures

According to the latest social-role theories, every human is a product of their surroundings, upbringing, community and culture.

Hence, gender roles, that most men and women naturally follow, are actually a result external forces and what they told to do.

According to the theory, parents, friends, movies, TV, magazines all project a certain role for each gender and if these external forces were eliminated, most children would grow up to be gender neutral.