Question

read the text.
what your nose knows
1 your sense of smell enriches your experience of the world around you. different scents can change your mood or transport you back to a distant memory. your ability to smell also plays a key role in your health. if your ability to smell declines, it can affect your physical well - being and everyday safety.
2 whether its freshly brewed coffee, pine trees in a forest, or smoke from a fire, the things we smell are actually the tiny molecules released by substances all around us. when we breathe in these molecules, they stimulate specialized sensory cells high inside the nose. each of these
what is the main focus of the text?
how our sense of smell is related to other senses
why our sense of smell declines more often than our other senses
why older people often suffer from smell loss
how our sense of smell works, and how and why it can decline

Explanation:

1. Analyze the first option: The text does not discuss the relationship between the sense of smell and other senses, so this option is incorrect.
2. Analyze the second option: The text does not compare the decline of the sense of smell with other senses, so this option is incorrect.
3. Analyze the third option: The text does not mention older people or smell loss related to age, so this option is incorrect.
4. Analyze the fourth option: The first part of the text (about scents and sensory cells) explains how the sense of smell works, and the part about the decline of the ability to smell explains how and why it can decline. This option matches the main focus of the text.

Answer:

how our sense of smell works, and how and why it can decline