**Core Concept**
Percentile is a measure used in statistics to express the relative standing of an individual's score in a group of scores. It represents the percentage of scores below a certain value in a dataset.

**Why the Correct Answer is Right**
Percentile is calculated by ranking the data from lowest to highest and dividing it into equal parts. The number of equal parts is determined by the percentile value, which ranges from 0 to 100. For example, a 25th percentile means that 25% of the data falls below this value. Percentiles are used in various fields, including medicine, to express the severity of a disease or the effectiveness of a treatment.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because a percentile does not divide the data into two equal parts, but rather into multiple equal parts.
**Option B:** This option is incorrect because there is no standard number of parts that percentiles divide data into, other than the percentile value itself.
**Option C:** This option is incorrect because percentiles are not typically used to divide data into more than 100 equal parts.

**Clinical Pearl / High-Yield Fact**
One important thing to remember is that percentiles can be misleading if not interpreted correctly. For example, a high percentile value does not necessarily mean that the individual's score is high, but rather that a large percentage of the data falls below that value.

**Correct Answer:** D. 100