Pleas help me i dont konw what to do

but it is sometime nessary to hit key points or subjects   but is sometimes to much reveiw if there was a way to slim down the redone work it would improve for every body.

the gas pressure p, gas volume v, and gas temperature t are given in the formula:   pv=nrt,

r is the gas constant, and n is the number of gas moles.

if the container is cooled and remains under atmospheric pressure, where r is a constant that does not change, the volume of the container remains the same, the conclusion is drawn that, with all other values ​​unchanged, the number of gas moles n, is decreases.

the right answer is a.