A doctor advised a person to take injection of insulin because:(a) his blood pressure was high(b) his heart beat was high(c) his blood sugar was high(d) his thyroxine level in blood was high

(c) his blood sugar was high.

The function of insulin hormone is to regulate the blood sugar (glucose) level in the body.  Hence, the doctor advised a person to take an injection of insulin to bring his sugar level to normal.