**Core Concept:** Gaussian distribution, also known as Normal distribution, is a continuous probability distribution that describes data that is spread out around a mean value. It is characterized by a bell-shaped curve and can be used to describe many natural phenomena, such as heights, weights, and blood pressure. The parameters of a Gaussian distribution are defined by its mean (μ) and standard deviation (σ).

**Why the Correct Answer is Right:** A Gaussian distribution is considered a "bell-shaped curve" because the majority of the data points cluster around the mean, with the probability density decreasing as we move away from the mean. The curve is symmetrical, with the peak at the mean and equal tails on both sides. The correct answer (D) focuses on the fact that the distribution is symmetrical and has equal tails. This is a key characteristic of a Gaussian distribution, as it indicates that the probability density is the same in both tails.

**Why Each Wrong Option is Incorrect:**

A. This option incorrectly states that Gaussian distribution is always unimodal. While most Gaussian distributions are unimodal, there can be bimodal distributions, where the data has two peaks, typically due to different subgroups within the data.

B. This option is incorrect because Gaussian distribution can have a skewed distribution, where the data is not symmetrical around the mean. This occurs when the standard deviation (σ) of one variable is significantly different from another, causing the curve to lean towards one side.

C. This option is incorrect as Gaussian distribution can have kurtosis, which refers to the distribution's peakedness. A normal distribution has a kurtosis value of 3, while other distributions can have higher or lower kurtosis values.

**Clinical Pearl / High-Yield Fact:** In statistics, it is essential to understand the properties of Gaussian distribution to analyze and interpret data effectively. The shape of a dataset can indicate whether it is closer to Gaussian, and thus, how well it can be modeled using this distribution.