What is expected when the reaction shown below takes place in a thermally-insulated container outfitted with a movable piston at a constant atmospheric pressure of 1 atm?

2C₂H₆(g) + 7O₂(g) → 4 CO₂(g) + 6H₂O(g)

a. Volume will decrease and work will be done on the system.
b. Volume will increase and work will be done by the system.
c. Volume will decrease and work will be done by the system.
d. Volume will increase and work will be done on the system.