**Core Concept:**
ANOVA (Analysis of Variance) is a statistical technique used to compare the means of three or more groups and determine if there are any significant differences between them. It is a powerful tool to analyze variance within and between groups.

**Why the Correct Answer is Right:**
ANOVA can be used in various clinical and research settings to compare the mean values of physiological or biochemical parameters across different groups. For instance, in a study evaluating the effectiveness of different medications on blood pressure, ANOVA can help identify which drug group has the lowest, highest, or significantly different blood pressure levels.

**Why Each Wrong Option is Incorrect:**
A. ANOVA is not applicable when comparing only two groups, as a t-test would be more suitable in such cases.
B. ANOVA is not used to compare continuous variables only, as other statistical tests like paired or unpaired t-tests would be more appropriate when dealing with continuous variables.
C. ANOVA assumes normality of data distribution, which may not be the case in all scenarios. However, appropriate methods like non-parametric tests (e.g., Kruskal-Wallis test) can be used when data is not normally distributed.
D. ANOVA is not limited to comparing continuous variables only; it can also be used for categorical variables (e.g., different disease severities) to determine if there are any significant differences between groups.

**Clinical Pearl / High-Yield Fact:**
When analyzing complex data with multiple groups, ANOVA allows researchers to identify which group(s) significantly differ from others, leading to more accurate conclusions and informed decision-making in clinical practice or research.

**Correct Answer:**
C. ANOVA is used to compare the means of three or more groups and determine if there are any significant differences between them.