The correct answer to the question is option 1: Adipose tissue. Adipose tissue, also known as fatty tissue, is the primary storage site for fat in the human body. It is a connective tissue that consists of specialized fat cells called adipocytes. These adipocytes store excess energy in the form of triglycerides, which are made up of fatty acids.

Adipose tissue is found throughout the body, with the highest concentration in certain areas such as the abdomen, thighs, and buttocks. Its main function is to regulate energy balance by storing and releasing fat as needed. Additionally, adipose tissue also provides cushioning and insulation to protect organs and tissues.

The other options provided in the question are not correct. While red blood cells do contain a small amount of fat in their membranes, they are not the primary storage site for fat. Muscle tissue is primarily composed of muscle fibers and does not store significant amounts of fat. Epithelial tissue, which covers the surfaces of organs and lines body cavities, is not involved in fat storage.

Therefore, the correct answer is option 1: Adipose tissue.