The Client Is Receiving Lithium (Eskalith) and Asks the Nurse

The client is receiving lithium (Eskalith) and asks the nurse why he has to have blood drawn so often. What is the best response by the nurse?

A) To determine if your body is responding as it should."
B) "To be sure you have the correct amount of medication in your system."
C) "To be sure the medication is working properly."
D) To detect side effects before they become a problem."