**Core Concept**
A Cohort study is a type of observational study where a group of individuals with a specific characteristic (cohort) is followed over time to examine the development of outcomes. This study design is often used to calculate incidence rates, relative risks, and odds ratios.

**Why the Correct Answer is Right**
In Cohort studies, the incidence rate of a disease or outcome is calculated by dividing the number of new cases by the person-time at risk in the cohort. This design allows researchers to assess the risk of developing a disease over time, making it suitable for calculating incidence rates.

**Why Each Wrong Option is Incorrect**
* **Option A:** (missing option, cannot provide explanation)
* **Option B:** (missing option, cannot provide explanation)
* **Option C:** (missing option, cannot provide explanation)
* **Option D:** (missing option, cannot provide explanation)

**Clinical Pearl / High-Yield Fact**
To remember the key differences between Cohort and Case-Control studies, recall that Cohort studies examine the development of outcomes over time (incidence), whereas Case-Control studies examine the risk factors associated with a pre-existing outcome (prevalence).

**Correct Answer:**
(To provide a complete explanation, you need to specify the options A, B, C, and D.)