**Core Concept**
The setting time of alginate impression material is influenced by the reaction between the alkaline earth metal salts (such as calcium sulfate or magnesium sulfate) and the acid groups in the alginate molecule, resulting in the formation of a gel-like mass. This reaction is known as acid-base neutralization.

**Why the Correct Answer is Right**
To control the setting time without altering the properties of the alginate impression material, the dentist can adjust the temperature of the water used to mix the material. Warmer water will accelerate the acid-base neutralization reaction, resulting in a faster setting time, while cooler water will slow down the reaction, allowing for a longer working time. This technique is known as "temperature control." The dentist can adjust the temperature to achieve the desired setting time without affecting the properties of the alginate, such as its elasticity, strength, or dimensional stability.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not address the chemical reaction that controls the setting time of alginate impression material.
**Option B:** This option is incorrect as altering the powder-to-liquid ratio can affect the properties of the alginate, such as its elasticity and strength, in addition to the setting time.
**Option C:** This option is incorrect as adding more water can lead to a weaker and more fragile alginate impression, which may not accurately capture the details of the dental impression.

**Clinical Pearl / High-Yield Fact**
A common mistake in dental impression taking is using water that is too cold, which can lead to a prolonged setting time and a weak or fragile alginate impression.

**Correct Answer: C. Adding more water.**