The correct answer is “the reaction is not affected at all”
An increase in pressure alters exactly the rate of reaction including reaction gases. Changing the pressure where there are just solids or liquids does not affect the rate of reaction. The reaction above is not an equilibrium, it is just forward. So, the reacting components, Mg (s) and HCl (aq) are solid and liquid. With this explained, we can conclude that the reactions does not change because of the pressure changes.
