Which of the Following Is a Factor in Explaining the Historical

Which of the following is a factor in explaining the historical low in the teenage birth rate?

A) the increasing price of condoms
B) adolescents taking the "virginity pledge" in schools across the country
C) the rates of sexual intercourse among teenagers have increased,and the use of birth control,such as condoms,has decreased
D) substitutions for sexual intercourse,such as oral sex,are increasingly accepted as an alternative to sexual intercourse