**Core Concept**
The mean radiant temperature is a measure used to describe the warmth or coolness perceived by a person due to radiation from their surroundings. This temperature is an important factor in the assessment of the thermal environment, particularly in the context of heat stress or cold stress.

**Why the Correct Answer is Right**
The mean radiant temperature is typically measured using a device called a globe thermometer. This thermometer consists of a hollow metal sphere coated with a black paint, which absorbs radiation from its surroundings. The temperature inside the globe thermometer is then used to estimate the mean radiant temperature, providing a more accurate assessment of the thermal environment. This measurement is particularly useful in indoor environments where convection and conduction may not accurately represent the temperature perceived by a person.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not specify a device or method for measuring the mean radiant temperature.
* **Option B:** This option is incorrect because it does not accurately describe a device or method for measuring the mean radiant temperature.
* **Option C:** This option is incorrect because it does not provide a valid device or method for measuring the mean radiant temperature.

**Clinical Pearl / High-Yield Fact**
It's essential to note that the mean radiant temperature can significantly affect a person's perception of temperature, especially in environments with low air movement. This makes the mean radiant temperature a critical factor in the assessment of heat stress or cold stress, particularly in occupational health settings.

**Correct Answer: C. Globe thermometer.**