**Core Concept**
The question is testing the understanding of a fundamental concept in medical testing and diagnostics, specifically the issue of false positives in a test. This concept is related to the **sensitivity and specificity** of a diagnostic test, which are measures of its ability to accurately identify true positives and true negatives.

**Why the Correct Answer is Right**
False positives occur when a test incorrectly identifies a healthy individual as diseased. One of the main reasons for false positives is the **low specificity** of a test. Specificity is the ability of a test to correctly identify true negatives (healthy individuals). When a test has low specificity, it means that it is prone to producing false positives. This can be due to various factors such as **cross-reactivity** of the test with other substances or conditions, **over-sensitivity** of the test, or **biases** in the test design.

**Why Each Wrong Option is Incorrect**
* **Option A:** Incorrect because while low sensitivity can lead to false negatives, it does not directly cause false positives.
* **Option B:** Incorrect because while high false discovery rate can be related to false positives, it is not the primary reason.
* **Option C:** Incorrect because while test sensitivity and specificity are related, low sensitivity is more closely related to false negatives.

**Clinical Pearl / High-Yield Fact**
A good diagnostic test should have both high sensitivity and high specificity to minimize false positives and false negatives. A common mnemonic to remember the key concepts of sensitivity and specificity is: **"Sn** (Sensitivity) is the ability to catch the disease when it's there (True Positive), while **Sp** (Specificity) is the ability to avoid catching the disease when it's not there (True Negative)".

**Correct Answer: D. Low specificity**