**Core Concept**
Chlorination of water is a critical step in ensuring the removal of pathogens and other microorganisms that can cause waterborne diseases. The proper level of chlorine in drinking water is essential for maintaining its safety and quality.

**Why the Correct Answer is Right**
The test used to determine the proper level of chlorine in water is the Orthotolidine (OT) test. This test is based on the reaction between chlorine and orthotolidine, a chemical compound that changes color in the presence of chlorine. When chlorine is added to the water sample, the orthotolidine reacts with it to form a yellow-colored compound, which is then measured spectrophotometrically to determine the concentration of free chlorine.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because there is no widely recognized test by this name for determining chlorine levels in water.
* **Option B:** This option is incorrect because the DPD (N,N-diethyl-p-phenylenediamine) test is actually used to measure the concentration of chlorine in water, but it is not the test mentioned in the question.
* **Option C:** This option is incorrect because there is no widely recognized test by this name for determining chlorine levels in water.

**Clinical Pearl / High-Yield Fact**
It is essential to note that the proper level of chlorine in drinking water is typically between 0.5 and 1.0 mg/L, as this concentration is sufficient to inactivate most pathogens without causing any adverse health effects.

**Correct Answer:** C.