By the age of 20, ___ of Americans have engaged in premarital sex

Mental health professionals operate under an assumption of __________, the perspective that human behavior is determined by biological, psychological, and social forces

Answer for this one, anyone?

Carla loves to work on her tan and feels safe because her family has no history of skin cancer. However, her doctor just a found a melanoma on her skin. The doctor points out that ultraviolet radiation from the sun can cause ________ that can lead to skin

a. pigmentation b. epigenetics c. mutations d. double-helixing