Choose the word which is different from the rest.

Thyroxine
Adrenaline
Iodine
Insulin

The answer is C. Iodine.

Thyroxine, adrenaline, and insulin are all hormones. Hormones are chemicals that are produced by glands in the body and that travel through the bloodstream to affect other parts of the body. Thyroxine is a hormone that is produced by the thyroid gland and that helps to regulate metabolism. Adrenaline is a hormone that is produced by the adrenal glands and that helps the body to respond to stress. Insulin is a hormone that is produced by the pancreas and that helps the body to use glucose for energy.

Iodine is a mineral that is essential for the production of thyroid hormones. However, it is not a hormone itself.