Final answer:
A tumor composed of fat is called a Lipoma, which is a benign fatty tissue growth, not to be confused with Melanoma, a severe form of skin cancer.
Step-by-step explanation:
The term that means a tumor composed of fat is A) Lipoma. A lipoma is a benign tumor made up of fat tissue. Unlike Melanoma, which is a malignant cancer originating from melanocytes in the skin, a lipoma is usually a noncancerous growth. Melanoma is the most fatal of all skin cancers and often presents as asymmetrical brown or black patches with uneven borders, whereas a lipoma is typically just a soft, rubbery bump under the skin.