**Core Concept**
The daily requirement of fat is a crucial aspect of nutrition, and its percentage of total energy intake is essential for maintaining optimal health. The human body requires a specific amount of fat for energy, hormone production, and absorption of fat-soluble vitamins.

**Why the Correct Answer is Right**
The correct answer is based on the recommended daily intake of fat by various health organizations. The World Health Organization (WHO) and other reputable sources suggest that fat should account for 20-35% of total energy intake. However, a more specific and commonly quoted recommendation is that fat should provide 20-25% of total energy. This range allows for the consumption of essential fatty acids, maintains energy balance, and supports the absorption of fat-soluble vitamins.

**Why Each Wrong Option is Incorrect**
* **Option A:** 10% is too low, as it would not provide sufficient energy for the body's needs, particularly for the brain and heart.
* **Option B:** 15% is also on the lower side, and may lead to inadequate energy supply for the body's functions.
* **Option D:** 25% is within the recommended range, but the more specific and commonly cited recommendation is 20%.
* **Option E:** 30% is higher than the recommended range and may lead to excessive fat intake, potentially contributing to obesity and other health issues.

**Clinical Pearl / High-Yield Fact**
A useful mnemonic to remember the daily requirement of fat is "FATS": 20-25% of total energy intake is essential for maintaining optimal health.

**Correct Answer: C. 20**