Packaged Cake Mixes Usually Contain Baking Powder, a Mixture of Sodium

Packaged cake mixes usually contain baking powder, a mixture of sodium hydrogen carbonate and calcium hydrogen phosphate that react to produce carbon dioxide gas when they are heated in water. The CO₂(g) formed allows the cake to "rise." When such cake mixes are used at high altitudes, often the cake will rise too much and collapse, unless special instructions are followed. Why does this happen

A) Due to the higher atmospheric pressure, a greater volume of carbon dioxide is created.
B) Due to the reduced atmospheric pressure, less volume of carbon dioxide is created.
C) Due to the reduced atmospheric pressure, a greater volume of carbon dioxide is created.
D) Due to the higher atmospheric pressure, less volume of carbon dioxide is created.
E) None of the above