**Core Concept**
The Absolute Parasite Rate (API) is a measure used to express the proportion of slides examined that are positive for a particular parasite, in this case, malaria. It is calculated as the number of positive slides divided by the total number of slides examined, multiplied by 100 to express it as a percentage.

**Why the Correct Answer is Right**
To calculate the API, we divide the number of positive slides (100) by the total number of slides examined (5000), and then multiply by 100. This gives us 100 / 5000 = 0.02 * 100 = 2. This means that 2% of the slides examined were positive for malaria. The API is a useful measure for monitoring the prevalence of a particular disease in a population.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not provided, so we will not discuss it.
* **Option B:** This option is not provided, so we will not discuss it.
* **Option C:** This option is not provided, so we will not discuss it.
* **Option D:** This option is not provided, so we will not discuss it.

**Clinical Pearl / High-Yield Fact**
The API is an important measure for monitoring the effectiveness of public health interventions and for identifying areas where more resources may be needed to control the spread of disease.

**Correct Answer: B. 2%**