A Client Had Pharmacogenetic Testing (PGx)two Years Ago,but the Prescriber

A client had pharmacogenetic testing (PGx) two years ago,but the prescriber has ordered another test prior to starting the client on tamoxifen.How should the nurse explain the need for this second test?

A) "Your first test was not normal."
B) "The testing you had last time must have been inconclusive."
C) "Your last test was not specific for tamoxifen."
D) "Your last test shows you have wild-type genes."