During a routine visit to the clinic, a client tells the nurse that she thinks she may be pregnant. The physician orders a pregnancy test. The nurse should know the purpose of this test is to determine which change in the client's hormone level?

a) Decrease in LH
b) Increase in human chorionic gonadotropin (HCG)
c) Increase in luteinizing hormone (LH)
d) Decrease in HCG