**Core Concept**
Chondrocytes are the only cells found in healthy cartilage, responsible for its maintenance and repair. The cartilage matrix, composed of collagen and proteoglycans, lacks a direct blood supply, making it essential for chondrocytes to obtain nutrients and oxygen through alternative means.

**Why the Correct Answer is Right**
Nutrient and oxygen diffusion across the perichondrium, a layer of dense connective tissue covering the cartilage, allows chondrocytes to survive. This process relies on the concentration gradient of these essential molecules, facilitating their movement from areas of high concentration (the surrounding bone and connective tissue) to areas of low concentration (the cartilage matrix). The perichondrium's permeability and the presence of diffusion channels enable this crucial exchange.

**Why Each Wrong Option is Incorrect**
**Option A:** Capillaries are not present within the cartilage matrix itself, making direct capillary supply an incorrect option. The absence of a direct blood supply necessitates alternative methods for chondrocyte nutrition.
**Option C:** Neurons are not involved in the delivery of nutrients and oxygen to chondrocytes. The nervous system plays a distinct role in sensing and controlling various bodily functions but is not responsible for supplying cartilage cells.
**Option D:** Active transport, a process involving the utilization of cellular energy to move substances against their concentration gradient, is not necessary for the exchange of nutrients and oxygen across the perichondrium. The diffusion process is sufficient for this purpose.

**Clinical Pearl / High-Yield Fact**
Cartilage's avascular nature makes it more susceptible to damage and less capable of regeneration compared to other tissues. This characteristic highlights the importance of preserving cartilage integrity and addressing any potential damage to prevent long-term consequences.

**✓ Correct Answer: B. Diffusion**