A doctor advised a person to take an injection of insulin because
(a) his blood pressure was low
(b) his heart was beating slowly
(c) he was suffering from goitre
(d) his sugar level in blood was high

(d) his sugar level in blood was high.

A person with diabetes will have high blood sugar because their body does not produce sufficient or no insulin hormones at all. To control blood sugar in these patients, insulin injections are given.