The Client Has Been Started on Detrol LA and Tells

The client has been started on Detrol LA and tells the nurse that he is experiencing constipation. What is the highest priority action on the part of the nurse?

A) Hold the next dose of the medication; this is an adverse reaction.
B) Administer the drug: this is an expected response to the drug.
C) Notify the physician; this is a side effect of the medication.
D) Call the pharmacist; this is evidence of toxicity of the drug.