In the human respiratory system, the contraction and relaxation of a muscle called the diaphragm helps move air through which of the following structures? A.
artery, capillary, and vein

B.
larynx, pharynx, and trachea

C.
atrium, trachea, and ventricle

D.
esophagus, kidney, and pharynx

when in a crucial situation, after calling 911, the correct posture for delivering effective compression is the proper hand placement.

first, place two fingers at the sternum, then put the heel of your other hand next to the fingers and place hand on top of the other. lock your elbows by using your body’s weight and compress the victim’s chest with a depth of 2 inches.

moreover, do 15 compression and 2 breaths, this process must be done four times until there is a pulse or a arrive.