Where are alveoli located in the human body?

Alveoli are found in the lungs

Tiny air sacs at the end of the bronchioles (tiny branches of air tubes in the lungs). The alveoli are where the lungs and the blood exchange oxygen and carbon dioxide during the process of breathing in and breathing out.

Explanation:

Where can you find alveoli and about how many are there in your body?

At the end of each bronchiole is a special area that leads into clumps of teeny tiny air sacs called alveoli (say: al-VEE-oh-lie).

There are about 600 million alveoli in your lungs and if you stretched them out, they would cover an entire tennis court.

i think a) betsy can donate only blood to mark is correct because, mark and betsy have the same blood type. whereas nobody else has b+ blood so betsy can't donate to them.