It is a thin muscles that contracts and relaxes to help the air go in and out?

How do the uv rays cause damage?   what exactly causes the skin to burn;   can you be more specific about this mechanism?   3. how do photosensitive medications increase a person's sensitivity to sunlight and therefore increase their risk of getting burned?     what kind of medications can increase photo-sensitivity, can you think of some examples?

What is the type of contaminant that can cause foodborne illness

Ijust want the meaning to life (no wrong or right answers i just want your true opinion)