What is the mist likely effect to the reaction is there is an increase in pressure on this reaction

B. The reaction rate decreases

Explanation:

Increasing the pressure on a reaction involving reacting gases increases the rate of reaction.  

Changing the pressure on a reaction that involves only solids or liquids has no effect on the rate.

If you increase the pressure of a gas, you squeeze it into a smaller volume

Greater density of molecules increases the number of collisions. When you decrease the pressure, molecules don't hit each other as often and the rate of reaction decreases.