**Core Concept**
Post-test probability of disease (PPV) is a measure of the likelihood that a patient has a disease given a positive test result. It is an essential concept in medical decision-making, particularly in the diagnosis and screening of diseases. The PPV is influenced by the sensitivity and specificity of the test, as well as the prevalence of the disease in the population.

**Why the Correct Answer is Right**
The PPV increases with the prevalence of the disease because a higher prevalence means that there are more cases of the disease in the population. When the disease is common, a positive test result is more likely to be true, resulting in a higher PPV. This is because the increased number of true positives (disease present and test positive) outweighs the increased number of false positives (disease absent and test positive). The formula for PPV is PPV = (Sensitivity x Prevalence) / ((Sensitivity x Prevalence) + (1 - Specificity) x (1 - Prevalence)), which demonstrates the direct relationship between PPV and prevalence.

**Why Each Wrong Option is Incorrect**
**Option B:** PPV decreases with prevalence because a lower prevalence means that there are fewer cases of the disease in the population, making a positive test result less likely to be true.
**Option C:** PPV is indeed related to prevalence, as demonstrated by the formula for PPV, which includes the prevalence of the disease in the numerator and denominator.
**Option D:** Accuracy is a separate concept that refers to the proportion of test results that are true (either true positive or true negative). While accuracy is related to PPV, it is not the same thing, and PPV is specifically concerned with the post-test probability of disease given a positive test result.

**Clinical Pearl / High-Yield Fact**
A useful mnemonic to remember the relationship between PPV and prevalence is "PPV goes up with Prevalence, down with Specificity". This highlights the importance of considering both the prevalence of the disease and the specificity of the test when interpreting PPV.

**✓ Correct Answer: A. Increases with prevalence**