Answer:
a)The volume is reduced to one-third of its original value.
Explanation:
For a gas at constant temperature, we can apply Boyle's law, which states that the product between pressure and volume is constant:

where p is the pressure and V the volume.
In our case, this law can also be rewritten as

where the labels 1 and 2 refer to the initial and final conditions of the gas.
For the gas in the problem, the pressure of the gas is tripled, so

And re-arranging the equation we find what happens to the volume:

so, the volume is reduced to 1/3 of its original value.