Plz tell fast plz

Dear Student,

Ans 1. Option c) is correct: Rings of cartilage
Rings of cartilage prevent collapse of trachea.

Ans 2. Option b) is correct: alveoli of lungs
Exchange of gases takes place in the alveoli of lungs.

Ans 3. Option b) is correct: Carbon dioxide
During exhalation we release carbon dioxide. So, the lime water turns milky due to carbon dioxide.

Ans 4. Option d) is correct: Statement II and 1V are true. 
Alveoli increases the surface area for exchange of gases. Also, in the alveoli, exchange of gases takes place i.e. oxygen from alveolar air diffuses into blood and carbon dioxide from blood into alveolar air. 

Regards