With reference to the c-shaped rings of the trachea, they:
a) are made of cartilage.
b) allow the esophagus to expand slightly into the tracheal space.
c) keep the trachea open for passage of air.
d) a and b are correct
e) a, b and c are correct

answer:

i believe the answer is d).

explanation:

i think this is because you are tearing apart the muscle, and then when you eat, the muscle re-heals, making itself even stronger.

edit: i put b) before but i meant to put d). sorry for the incorrect answer.

answer: depends on how munch your body can take ( personal advice use 6 lines then quit)

explanation: