**Core Concept**
Positively skewed distribution, also known as right-skewed distribution, is a type of distribution where the majority of the data points are concentrated on the left side of the graph, with a few extreme values or outliers on the right side. This type of distribution is often seen in medical data, such as laboratory test results, where there are many normal or near-normal values and a few abnormal values.

**Why the Correct Answer is Right**
In a positively skewed distribution, the mean is typically greater than the median, due to the influence of the extreme values on the right side of the graph. This is because the mean is sensitive to outliers, whereas the median is more resistant to extreme values. In medical statistics, positively skewed distributions are often seen in data that is not normally distributed, such as blood pressure measurements or serum creatinine levels.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the characteristics of a positively skewed distribution.
**Option B:** This option is incorrect because it suggests that the median is greater than the mean, which is not true in a positively skewed distribution.
**Option C:** This option is incorrect because it does not provide a clear description of the distribution.

**Clinical Pearl / High-Yield Fact**
When analyzing medical data, it's essential to consider the distribution of the data, as it can significantly impact the interpretation of the results. In particular, positively skewed distributions can lead to inaccurate conclusions if not properly addressed.

**Correct Answer:** D.