**Core Concept**
The question is related to the purification of drinking water, specifically the removal of cysts (cyclops) from water. The underlying principle involves the use of disinfectants to kill or inactivate pathogens, including protozoa like cyclops.

**Why the Correct Answer is Right**
Cysts are resistant to chemical disinfection but can be killed by heat. The correct answer involves using heat to pasteurize water, which is an effective method to remove cysts. Pasteurization involves heating water to a temperature of at least 70°C (158°F) for a short duration, usually 15-30 minutes. This process denatures proteins and disrupts the cell membrane of cysts, ultimately killing them.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option does not relate to the removal of cysts from water.
* **Option B:** Chlorination is a common method for disinfecting water, but it is not effective against cysts. Chlorine can penetrate the cyst wall and kill the organism inside.
* **Option D:** This option does not seem to be directly related to the removal of cysts from water.

**Clinical Pearl / High-Yield Fact**
When it comes to water purification, heat treatment (pasteurization) is an effective method to remove cysts and other resistant pathogens. This method is commonly used in the food and beverage industry, as well as in some water treatment plants.

**Correct Answer:** C.