When the price of insulin is $10, consumers demand 100 units; when the price is $15, consumers demand 100 units; and when the price is $20, consumers demand 100 units. Based on this information, the demand for insulin is:

When the price of insulin is $10, consumers demand 100 units; when the price is $15, consumers demand 100 units; and when the price is $20, consumers demand 100 units. Based on this information, the demand for insulin is:

A.elastic

B.unit elastic

C.perfectly elastic

D.perfectly inelastic

正确答案：perfectly inelastic