Answer:
b) the reaction proceeds to a new equilibrium in the direction that offsets the change.
Explanation:
According to Le Chatelier's principle, when a system experiences a constraint such as a change in pressure, temperature or concentration, the system will readjust itself in order to annul the constraint.
This simply means that when temperature, concentration or pressure is changed, a new equilibrium position is reached in order to offset the changes in the system.
I'm pretty sure all 4 are subatomic particles but if i had to guess i'd be Photons
Replacement I think, hope this helps ;)
Explanation: