Which of the following glands is the largest in an adult human?

Which one of the following pairs of organs includes only endocrine glands?

The hormone prolactin was discovered by:

Which of the following is called the "biological middleman"?

The secretions of endocrine glands are released directly

Correct the following statements by replacing the incorrect terms:
$(a)$ Insulin is a steroid hormone.
$(b)$ $TSH$ is secreted from the corpus luteum.
$(c)$ Tetraiodothyronine is an emergency hormone.
$(d)$ The pineal gland is located on the anterior part of the kidney.