Answer the following question given this paragraph: 

You can see an example of a negative feedback loop in Figure below . It shows how levels of thyroid hormones regulate the thyroid gland. This loop involves the hypothalamus and pituitary gland as well as the thyroid gland. Low levels of thyroid hormones in the blood cause the release of hormones by the hypothalamus and pituitary gland. These hormones stimulate the thyroid gland to secrete more hormones. The opposite happens with high levels of thyroid hormones in the blood. The hypothalamus and pituitary gland stop releasing hormones that stimulate the thyroid.


Q: Low levels of thyroid hormones in the blood cause the release of what by the hypothalamus and pituitary gland?

 Choices:

- acids

- bases

- enzymes

- hormones

A:
hormones
