Infertility is usually defined as: select one: a. childlessness. b. the inability to conceive after one year of unprotected intercourse. c. the inability to conceive after ten years of unprotected intercourse. d. sterilization.

I believe the answer is: b. the inability to conceive after one year of unprotected intercourse

In united states, the rate of infertility among women is around 12% and 15% among men .The most common causes of infertility, are :low sperm count, improper temperature within the female host's body, and hormonal imbalance in the host's body 

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Afine-grained igneous rock forms as a result of slow cooling.