## **Core Concept**
The question tests knowledge of human physiology, specifically the **salivary gland** function and **daily saliva production**. Saliva plays a crucial role in digestion, oral health, and facilitating speech.

## **Why the Correct Answer is Right**
The correct answer, **1-2 liters**, accurately reflects the average daily saliva production in humans. This volume is crucial for maintaining oral health, facilitating digestion, and ensuring proper speech. The **major salivary glands** (parotid, submandibular, and sublingual glands) contribute to this volume, with the **submandibular glands** producing the largest portion.

## **Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it underestimates the total daily saliva production.
* **Option B:** This option is incorrect because it suggests a range that is too broad and not specific to the average daily production.
* **Option D:** This option is incorrect because it overestimates the total daily saliva production.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that **hyposalivation** (reduced saliva production) can lead to dental caries, difficulty swallowing, and altered taste. Conversely, **hypersalivation** can cause drooling and speech difficulties.

## **Correct Answer:** C. 1-2 liters.