**Core Concept**
The primary gland responsible for thermoregulatory sweating in humans is the eccrine gland, which plays a crucial role in maintaining body temperature through the evaporation of sweat. This process is mediated by the hypothalamus, which acts as the body's thermostat, regulating sweat production in response to changes in core body temperature.

**Why the Correct Answer is Right**
The eccrine gland is the primary sweat gland responsible for thermoregulatory sweating. It is distributed all over the body, but is most concentrated on the palms of the hands, soles of the feet, and forehead. These areas are richly innervated with sympathetic nerve fibers that stimulate sweat gland activity in response to increased core body temperature. The eccrine gland secretes a hypotonic solution that evaporates quickly, cooling the body through the process of evaporation.

**Why Each Wrong Option is Incorrect**
**Option A:** Apocrine glands are primarily involved in the production of pheromones and are found in the axillary and anogenital regions. They are not responsible for thermoregulatory sweating.

**Option B:** Sebaceous glands produce sebum, an oily substance that helps to lubricate and protect the skin. They are not involved in sweat production or thermoregulation.

**Option C:** Mucous glands produce mucus, a thick, protective substance that helps to trap dust and other particles in the respiratory and gastrointestinal tracts. They are not involved in sweat production or thermoregulation.

**Clinical Pearl / High-Yield Fact**
The hypothalamus acts as the body's thermostat, regulating sweat production and other thermoregulatory mechanisms in response to changes in core body temperature. This is why patients with hypothalamic dysfunction, such as those with hypothalamic tumors or damage, may experience abnormal temperature regulation and sweating patterns.

**Correct Answer: C. Eccrine glands are the primary sweat glands responsible for thermoregulatory sweating in humans.**