Which layer of the skin is described as the thicker and fatter tissue?

The subcutaneous layer is the correct choice as it serves as the thicker and fatter tissue beneath the dermis. This layer is primarily composed of loose connective tissue and fat cells, which provide insulation, cushioning, and energy storage. It also plays a crucial role in anchoring the skin to underlying structures such as muscles and bones.

The epidermis, being the outermost layer of the skin, is composed of stratified epithelial cells and does not contain fat or provides insulation. The dermis lies beneath the epidermis and is thicker than the epidermis, containing connective tissue, hair follicles, sweat glands, and is more fibrous rather than fatty. The hypodermis is often used interchangeably with the subcutaneous layer, but the term "subcutaneous" more accurately reflects the fatty nature of the layer in the context of this question. Thus, the subcutaneous layer is specifically known for its thicker, fatty tissue composition.