Plz
which punctuation mark is missing in the sentence?
put the bread dough into the
a) ?
b) .
c) !

this is what i put and it was correct

it's a way for authors to communicate with reader in this time period. books from the past can teach us about life.

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.