**Core Concept:** Rods and cones are types of photoreceptor cells in the retina of the eye, responsible for vision in low and high light conditions, respectively. Rods are more numerous and sensitive to light, while cones are less numerous but provide color vision.

**Why the Correct Answer is Right:** Rods and cones differ in their function, sensitivity, and distribution in the retina. Rods are responsible for vision in low light conditions, while cones are responsible for color vision and function best in bright light. Rods are more sensitive but less specific than cones, which are less sensitive but more specific to certain light intensities. The correct answer is not mentioned, but it is essential to understand the main differences between rods and cones.

**Why Each Wrong Option is Incorrect:**

A. Sensitivity: Both rods and cones are sensitive to light, but rods are more sensitive than cones.
B. Distribution: Rods and cones are distributed differently in the retina. Rods are concentrated peripherally, while cones are concentrated in the central part of the retina (macula).
C. Function: The main difference between rods and cones is their function – rods for low light vision and cones for color vision.
D. Specificity: Cones are more specific to certain light intensities, whereas rods are less specific.

**Clinical Pearl:** Understanding the differences between rods and cones is crucial for understanding vision under various light conditions and recognizing ocular pathologies affecting them, such as retinitis pigmentosa, which is a group of inherited diseases affecting rod and cone cells, leading to progressive vision loss.

**Correct Answer:** D. Sensitivity: Both rods and cones are sensitive to light, but rods are more sensitive than cones.