What is the mechanism which causes air to enter a person’s lung when inhaling?: The decrease in lung volume.
The chemical difference between oxygen and carbon dioxide .
The force of the person drawing in air by breathing.
The difference in atmospheric pressure in the lungs.

I believe it;s the difference in pressure

Explanation:

This is caused by the diaphragm contracting and therefore expanding the thoracic cavity. This increase in volume causes a decrease in pressure.

maybe

only if le monke lets me

the treatment of other conditions (e.g., cystic breast disease) and for other medical reasons. Mastectomy is most effective when the cancerous tumour is discovered at an early stage and the malignant cells are localized. In order to best ensure the removal of all cancerous tissue, however, a margin of tissue surrounding a tumour and, sometimes, other nearby structures are also removed. Thus, there are several types of mastectomy, the selection of procedure depending on the location and extent of the disease (determined by X ray, thermography, and other diagnostic techniques) and the nature of the cancerous cells (determined by biopsy).

Explanation:

^^