**Core Concept**
Chlorine is a disinfectant commonly used in water treatment to kill bacteria, viruses, and other microorganisms. The disinfecting action of chlorine is primarily due to its ability to form compounds that are toxic to microorganisms.

**Why the Correct Answer is Right**
The disinfecting action of chlorine is mainly attributed to the formation of hypochlorous acid (HOCl) and hypochlorite ions (OCl-). These compounds are strong oxidizing agents that denature proteins, disrupt cell membranes, and interfere with metabolic processes, ultimately leading to the death of microorganisms. The formation of HOCl is facilitated by the reaction of chlorine with water, which is a critical step in the disinfection process.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because the formation of chloramine (NH2Cl) is not the primary mechanism of chlorine's disinfecting action. While chloramines do have some disinfecting properties, they are not as effective as HOCl and OCl-.
**Option B:** Incorrect because the formation of hydrochloric acid (HCl) is a byproduct of chlorine's reaction with water, but it is not responsible for the disinfecting action of chlorine.
**Option C:** Incorrect because the formation of sodium chloride (NaCl) is a result of the reaction of chlorine with sodium hydroxide, but it is not related to the disinfecting action of chlorine.

**Clinical Pearl / High-Yield Fact**
Remember that the pH of the water can affect the formation of HOCl and OCl-, with optimal disinfection occurring at a pH range of 6.5-7.5.

**Correct Answer:** C.