**Core Concept**
The standard normal distribution, also known as the z-distribution, is a probability distribution of a normally distributed variable with a mean of 0 and a standard deviation of 1. This distribution is used to standardize scores and compare them across different populations.

**Why the Correct Answer is Right**
The standard normal distribution is essential in statistics and research, allowing for the calculation of probabilities and percentiles. It is used in hypothesis testing, confidence intervals, and regression analysis. The z-score formula, z = (X - μ) / σ, where X is the value, μ is the mean, and σ is the standard deviation, is used to transform raw scores into standard units. This transformation enables the calculation of probabilities using the standard normal distribution table or calculator.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not a characteristic of the standard normal distribution.
**Option B:** This option is incorrect, as the standard normal distribution has a mean of 0, not 1.
**Option C:** This option is not a correct description of the standard normal distribution.

**Clinical Pearl / High-Yield Fact**
Remember that the standard normal distribution is a special case of the normal distribution, and it is used to standardize scores and compare them across different populations.

**Correct Answer:** D.