Answer:
C. Gallbladder
Step-by-step explanation:
Endocrine glands release/secrete hormones into the bloodstream.
The Gallbladder is not an endocrine gland as it does not secrete anything, but stores bile that is produced by the liver.
The hypothalamus produces hormones that help to control many things, some including body temperature, heart rate, and hunger, and therefore is a part of the endocrine system.
Testes produce and secrete a hormone called testosterone, therefore they are considered to be a part of the endocrine system.
The pineal gland secretes melatonin, which helps control the sleep/wake cycle, and is therefore a part of the endocrine system.
The adrenal gland secretes hormones that regulate many things, some including the immune system, blood pressure, metabolism, etc, and is therefore a part of the endocrine system.