Fact 1: Insulin helps cells take up glucose from the blood.

Fact 2: For example, insulin is a protein hormone.

Given the two facts above, answer the question "What helps cells take up glucose from the blood?" with the following options: 
- Chemical energy
 - Veins and arteries.
 - layers of fat
 - sweating
 - protein hormones
 - aqueous solution
 - oxidation reaction
 - pancreas


 

     protein hormones    