**Core Concept**
The question is inquiring about the ventilation requirements in a living room, specifically the number of air changes per hour. This is related to the concept of indoor air quality and the need to remove stale air and replace it with fresh air to maintain a healthy environment.

**Why the Correct Answer is Right**
The American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) recommends a minimum of 4 air changes per hour in living rooms. This is based on the idea that a certain volume of air should be exchanged with the outside environment to remove pollutants, odors, and moisture. In a living room, this is particularly important to remove volatile organic compounds (VOCs) and other pollutants that can accumulate from furniture, carpets, and human activities.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is too low and would likely lead to poor indoor air quality, potentially causing health issues such as headaches, fatigue, and respiratory problems.
**Option B:** This option is too high and would result in excessive energy consumption and potentially higher heating and cooling bills.
**Option C:** This option is not a specific recommendation and could be confusing.

**Clinical Pearl / High-Yield Fact**
A good rule of thumb for indoor air quality is to ensure that the ventilation rate is at least 4 air changes per hour in living spaces, and 6-8 air changes per hour in areas with high occupancy or where pollutants are more likely to accumulate.

**Correct Answer: C. 6 air changes per hour.**