according to the quantity theory of money, changes in which variable(s) from the equation of exchange…

Brief Explanations:

The equation of exchange in the quantity - theory of money is $MV = PY$, where $M$ is the money supply, $V$ is the velocity of money, $P$ is the price level, and $Y$ is real output. In the long - run, it is assumed that real output $Y$ is determined by factors of production and technology and is relatively stable, and the velocity of money $V$ is also stable. So, changes in the money supply $M$ directly determine changes in the price level $P$, which is related to the rate of inflation.

Answer:

E. M only