Can someone give me the missing word?

Is this a single replacement reaction or there is no

*will mark you brainliest + 15 points ** why does the equilibrium of a system shift when the pressure is increased? a. to maximize the stress on the system b. to stop restoring equilibrium to the system c. to increase the total moles of gas in the system d. to decrease the total moles of gas in the system

When the mercury level in a barometer decreases that atmospheric pressure has