Wrinkles
Skin wrinkles are caused by a variety of factors. Some of these factors are intrinsic, meaning that you cannot control them because they occur naturally. Others are extrinsic, meaning that they are caused by circumstances outside of the body.
One intrinsic factor is aging. As you age, your skin loses collagen, which is the protein responsible for keeping your skin elastic. With less collagen, your skin becomes thinner and more fragile. Aging also reduces the functioning of sweat and oil glands, which work to keep the skin looking smooth. You also lose fat in the deeper layers of your skin as you age. This fat loss causes your skin to sag and develop deeper wrinkles.
The two most common extrinsic factors are exposure to ultraviolet radiation (UV rays) and smoking. UV rays in sunlight break down your skin's connective tissue and collagen fibers. To prevent the appearance of wrinkles (as well as protect yourself from skin cancer), you should always use UV-blocking sunscreen. The nicotine in cigarettes is the most likely link between smoking and wrinkles. Nicotine narrows the blood vessels, reducing the blood supply to your skin tissue. This deprives your skin of oxygen and important nutrients, causing damage that contributes to wrinkles.
Question: Why does the author include information regarding UV-blocking sunscreen?

Question

Wrinkles
Skin wrinkles are caused by a variety of factors. Some of these factors are intrinsic, meaning that you cannot control them because they occur naturally. Others are extrinsic, meaning that they are caused by circumstances outside of the body.
One intrinsic factor is aging. As you age, your skin loses collagen, which is the protein responsible for keeping your skin elastic. With less collagen, your skin becomes thinner and more fragile. Aging also reduces the functioning of sweat and oil glands, which work to keep the skin looking smooth. You also lose fat in the deeper layers of your skin as you age. This fat loss causes your skin to sag and develop deeper wrinkles.
The two most common extrinsic factors are exposure to ultraviolet radiation (UV rays) and smoking. UV rays in sunlight break down your skin's connective tissue and collagen fibers. To prevent the appearance of wrinkles (as well as protect yourself from skin cancer), you should always use UV-blocking sunscreen. The nicotine in cigarettes is the most likely link between smoking and wrinkles. Nicotine narrows the blood vessels, reducing the blood supply to your skin tissue. This deprives your skin of oxygen and important nutrients, causing damage that contributes to wrinkles.
Question: Why does the author include information regarding UV-blocking sunscreen?

Quizplus · Accepted Answer

The author includes this statement to explain how UV damage can lead to wrinkles and also states that "you should always use UV-blocking sunscreen" in order to prevent the appearance of wrinkles.
To support the idea that UV rays are an extrinsic factor is incorrect. Although UV rays are an extrinsic factor, UV-blocking sunscreen does not support the idea anymore so than another detail in the text.
To introduce the idea of skin cancer and change topics is incorrect. Although the author mentions skin cancer and states that it, too, can be protected against by sunscreen, the author does not change topics with the inclusion of this detail.
To introduce the idea regarding smoking and nicotine as additional extrinsic factors is incorrect. Although the author immediately discusses smoking and nicotine after this detail in question, the fact that UV-blocking sunscreen is included does not serve to introduce the topic of smoking.

Wrinkles Skin Wrinkles Are Caused by a Variety of Factors. Some