Two year olds sleep between these many hours at night time. a. 12 - 13 hours b. 9 - 12 hours c. 8 - 9 hours d. none of the above

The cardiovascular system, which transports blood through the body, is a one-way system. select the best answer from the choices provided. t f

Which of these is most likely to prevent pregnancy? a. tracking of female body temperature to identify ovulation times b. proper condom use c. male withdrawal before ejaculation d. proper spermicide use

What do you generally see in a family when both parents are working?