Answer: B. The pituitary gland.
Step-by-step explanation:
There are three glands of the endocrine system that are located in your brain; the hypothalamus, the pineal gland, and the pituitary gland.
By looking at any diagram on the internet, you can clearly see that the pituitary gland is located near the ear on the side of your head.
I linked a diagram for more clarification.
Hope this helped!