Why do people need to have sex to have a child?

Which type of food have a high amount of nutrients relative to the number of calories

Mucous membranes.. a. cover or line external surface of body. b. line internal body surfaces that are in contact with the environment. c. produce antibodies to combat infection. d. secrete sweat, which has antibacterial enzymes.

What is the only part of your body called that should touch the ball when setting in volleyball?