**Core Concept**
Oxygen-dependent killing is a mechanism employed by certain cells of the immune system to eliminate ingested microbes. This process involves the production of reactive oxygen species (ROS) that damage the microbial cell membrane, ultimately leading to its destruction. The key enzyme responsible for this process is NADPH oxidase.

**Why the Correct Answer is Right**
Oxygen-dependent killing is primarily carried out by phagocytic cells, such as neutrophils and macrophages. When these cells engulf a microbe, they generate a burst of ROS through the action of NADPH oxidase. This enzyme catalyzes the reduction of oxygen to superoxide (O2-), which is then converted to other ROS, such as hydroxyl radicals and hydrogen peroxide. These reactive species damage the microbial cell membrane, disrupting its function and ultimately leading to the death of the microbe.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the oxygen-dependent killing mechanism. While antimicrobial peptides do play a role in the immune response, they are not responsible for oxygen-dependent killing.
**Option B:** This option is incorrect because it refers to a different mechanism of microbial killing, one that is independent of oxygen. The nitric oxide-dependent killing pathway involves the production of nitric oxide (NO) by inducible nitric oxide synthase (iNOS).
**Option C:** This option is incorrect because it is not a mechanism of microbial killing. While the complement system does play a role in the immune response, it is not responsible for oxygen-dependent killing.

**Clinical Pearl / High-Yield Fact**
The oxygen-dependent killing mechanism is critically dependent on the availability of oxygen. In low-oxygen environments, such as those found in certain infections or in areas of tissue ischemia, the immune response may be impaired, allowing microbes to proliferate unchecked.

**Correct Answer:** C.