The graph shows the potential energy diagram for an unknown chemical change. A graph is shown with an inverted graph curve. The curve starts at a higher position on the left side and ends at a lower position on the right side. The higher left position has Reactants written below it and the lower right position has Products written below it. The y axis of the graph has the title Potential Energy with kJ written in parentheses. There is an arrow pointing upwards which is parallel to the y axis. The x axis of the graph has Reaction Pathway along with an arrow pointing towards the right.

Which chemical change could the graph represent? (1 point)

a
Adding heat to decompose calcium carbonate

b
Photosynthesis in plants

c
Electrolysis of water

d
Combustion of iron