**Core Concept**
Every 10th person being selected from a population is an example of a systematic sampling method, where the selection of subjects is done in a predetermined order. This approach is based on the principle of sampling intervals, where the researcher selects every nth individual from the population.

**Why the Correct Answer is Right**
Systematic sampling involves selecting samples based on a fixed interval, which in this case is every 10th person. This method is often used when the population is large and it's impractical to conduct a census. The researcher starts with a random selection of the first individual and then selects every nth individual thereafter. This technique can provide a representative sample of the population, as long as the sampling interval is not too large.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because cluster sampling involves selecting a group of people who share similar characteristics, rather than selecting individuals based on a fixed interval.
**Option B:** This option is incorrect because stratified sampling involves dividing the population into distinct subgroups and then selecting individuals from each subgroup, rather than selecting individuals based on a fixed interval.
**Option C:** This option is incorrect because convenience sampling involves selecting individuals who are easily accessible or convenient to sample, rather than selecting individuals based on a fixed interval.

**Clinical Pearl / High-Yield Fact**
Systematic sampling is a type of probability sampling, which means that every individual in the population has a known chance of being selected. This approach can provide a representative sample of the population, but it requires careful consideration of the sampling interval to ensure that the sample is representative.

**Correct Answer: C. Systematic sampling. This type of sampling is also known as interval sampling.**