Which layer of the skin contains blood vessels and nerve endings?

The dermis is the correct choice because it is the middle layer of the skin and is rich in connective tissue, making it the primary layer where blood vessels and nerve endings are located. This layer also houses a variety of structures, including hair follicles, sweat glands, and sebaceous glands, all of which play crucial roles in thermoregulation, sensation, and protection.

The blood vessels in the dermis provide nutrients and oxygen to the skin and help in regulating body temperature by controlling blood flow to the skin's surface. The presence of nerve endings allows for the detection of sensations such as touch, pain, temperature, and pressure, making the dermis essential for the sensory function of the skin.

In contrast, the stratum corneum is the outermost layer of the epidermis, composed mainly of dead keratinized cells and devoid of blood vessels and nerve endings. The hypodermis, or subcutaneous layer, lies beneath the dermis and contains larger blood vessels and fat cells, but it is not considered a primary layer of the skin. The stratum basale is the deepest layer of the epidermis, mainly responsible for the generation of new skin cells, and also lacks direct blood supply and extensive nerve endings.