Sebum protects the skin from which of the following?

• A. Mechanical injury
• B. Ultraviolet radiation
• C. Cold temperatures
• D. Dehydration

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the role of sebum in the skin. Sebum is an oily substance secreted by sebaceous glands in the skin. Its primary function is to lubricate and waterproof the skin and hair, preventing dryness and dehydration.
2. Step 2: Analyze the options provided in the question. Mechanical injury, ultraviolet radiation, and cold temperatures are external factors that sebum does not directly protect against. Instead, sebum forms a barrier to reduce water loss from the skin.
3. Step 3: Relate the function of sebum to dehydration. Sebum helps maintain the skin's moisture by preventing excessive evaporation of water from the skin's surface, which is crucial for hydration.
4. Step 4: Eliminate incorrect options. Mechanical injury, ultraviolet radiation, and cold temperatures are not directly mitigated by sebum. These factors require other protective mechanisms, such as the skin's structure or melanin production.
5. Step 5: Conclude that the correct answer is dehydration, as sebum's primary role is to prevent water loss and maintain skin hydration.