The Patient Asks the Nurse,"My Doctor Says I Get Confused

The patient asks the nurse,"My doctor says I get confused sometimes because I have vascular dementia.What caused me to have that?" The most appropriate response by the nurse would be:

A) "It is usually caused from damage to brain cells because of inadequate blood supply, like a small stroke."
B) "It is probably just some abnormal electrical activity in your brain."
C) "You probably have a brain tumor."
D) "I'm sure he will explain it to you later."