James Is a 52-Year-Old Overweight Smoker Taking Theophylline for His

James is a 52-year-old overweight smoker taking theophylline for his persistent asthma. He tells his provider he is going to start the Atkin's diet for weight loss. The appropriate response would be:

A) Congratulate him on making a positive change in his life.
B) Recommend he try stopping smoking instead of the Atkin's diet.
C) Schedule him for regular testing of serum theophylline levels during his diet due to increased excretion of theophylline.
D) Decrease his theophylline dose because a high-protein diet may lead to elevated theophylline levels.