## Core Concept
Sweat glands, also known as sudoriferous glands, are a type of exocrine gland. Exocrine glands are characterized by their ability to secrete substances onto the surface of the skin or into ducts that lead to the skin surface.

## Why the Correct Answer is Right
The correct answer, **eccrine glands**, refers to a specific type of exocrine gland that is widely distributed over the body surface. Eccrine sweat glands are involved in thermoregulation, and their secretions help to cool the body through evaporation. These glands are present from birth and are found all over the body, particularly on the palms, soles, and forehead.

## Why Each Wrong Option is Incorrect
* **Option A:** Apocrine glands are a type of exocrine gland but are primarily involved in secreting a protein-rich substance that, when broken down by bacteria, leads to body odor. They are mainly found in the armpits and genital area and are not the primary type of sweat gland.
* **Option B:** Holocrine glands secrete their product by releasing entire cells, which disintegrate to release their product. While apocrine glands are a type of holocrine gland, eccrine glands are not; eccrine glands release their secretions through exocytosis without losing part of the cell.
* **Option D:** Merocrine glands are another term for eccrine glands, particularly in the context of sweat glands. However, the term "merocrine" is sometimes used interchangeably with eccrine to describe glands that secrete their products through exocytosis without significant cellular damage.

## Clinical Pearl / High-Yield Fact
A key point to remember is that **eccrine glands** are crucial for thermoregulation and are present all over the body, whereas **apocrine glands** are mainly limited to the axillary and genital regions and are not active until puberty.

## Correct Answer: C. eccrine glands