A driver presenting to your office marks down that he is taking "nitroglycerine" for angina and he has been doing so for a few years. Upon questioning he indicates that he has needed more recently because his episodes have become more frequent. Your best course of action is to?
a) Counsel the driver to increase his dose of medication.
b) Certify the driver for 1 year.
c) Provide a 1-time, 3 month certificate to monitor his condition.
d) Disqualify the driver and refer him to his cardiologist for further evaluation.