**Core Concept**
Carotid body receptors are specialized chemoreceptors that detect changes in the chemical composition of arterial blood, particularly the levels of oxygen, carbon dioxide, and pH. These receptors play a crucial role in regulating breathing and maintaining acid-base balance.

**Why the Correct Answer is Right**
The correct answer is related to the stimulation of carotid body receptors by a specific condition. Carotid body receptors are sensitive to low oxygen levels (hypoxia), high carbon dioxide levels (hypercapnia), and acidosis. When these conditions occur, the carotid body receptors are stimulated, leading to an increase in the activity of the respiratory centers in the brain, resulting in increased ventilation and attempts to correct the imbalance.

**Why Each Wrong Option is Incorrect**
**Option A:** Low blood pressure is not a direct stimulus for carotid body receptors. While hypotension can lead to decreased oxygen delivery to tissues, it is not the primary stimulus for carotid body receptor activation.
**Option B:** High blood sugar levels are not directly detected by carotid body receptors. While hyperglycemia can lead to acidosis and other metabolic disturbances, it is not the primary stimulus for carotid body receptor activation.
**Option C:** Low temperature is not a direct stimulus for carotid body receptors. While hypothermia can lead to decreased metabolic rate and decreased oxygen consumption, it is not the primary stimulus for carotid body receptor activation.

**Clinical Pearl / High-Yield Fact**
The carotid body receptors are sensitive to changes in the partial pressure of oxygen (pO2), with a threshold of around 60 mmHg. Below this threshold, carotid body receptor stimulation leads to increased ventilation and attempts to correct the hypoxia.

**Correct Answer:** D. Low oxygen levels (hypoxia)