<prompt> In basal body temperature method, after the rise of temperature, the unsafe period lasts for :-24 hours48 hours72 hours120 hours  <response>: - In BBT, the rise of temperature signifies ovulation. - Since maximum survival of ovum post ovulation is 3 days, the unsafe period is 3 days post rise of body temperature. Other natural methods of contraception are: Calender method feile period method safe period method rhythm method Cervical mucus method Symptothermic method Coitus interruptus Abstinence - most effective method 