**Core Concept**
The power of a study refers to its ability to detect a statistically significant difference between two groups. Increasing the power of a study allows researchers to detect smaller effects and reduces the risk of Type II errors (false negatives). This is crucial in medical research, as it enables the identification of potential treatments or interventions that may have a significant impact on patient outcomes.

**Why the Correct Answer is Right**
Increasing the power of a study can be achieved by several methods. One of these is by **increasing the sample size**. When more participants are included in the study, the study has a greater ability to detect statistically significant differences between groups. This is because larger sample sizes provide more precise estimates of population parameters, such as means and proportions. Additionally, increasing the sample size also allows researchers to detect smaller effects, which may be clinically significant.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to increasing the power of a study.
**Option B:** While reducing the alpha level (e.g., from 0.05 to 0.01) can increase the power of a study, it is not the most effective method. Reducing the alpha level increases the risk of Type I errors (false positives).
**Option C:** This option is not a valid method for increasing the power of a study.

**Clinical Pearl / High-Yield Fact**
A commonly used mnemonic to remember the factors that increase the power of a study is "MORE POWER": Multiply the sample size, Obtain more precise estimates, Reduce the alpha level, and Employ more sensitive statistical tests.

**Correct Answer: A. Increasing the sample size**