The idea of spontaneous generation was disproved by in an experiment involving jars of meat.

Explanation:

In 1668, Redi decided to try to disprove spontaneous generation, which was the thought the flies came from rotten meat and other animals came from nonliving things. He put two indentical pieces of meat in jars. He left one covered and the other uncovered. The uncovered meat teamed with flies, which the covered meat did not. Redi concluded that meat doesn't create flies, but rather the flies are attracted to the meat.

a and b

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.