All of the following conditions in earth can cause metamorphic rocks to form except
a. exposure to air
c. heat
b. the presence of hot, watery fluids
d. pressure

Metamorphic rocks are the rocks formed from other rocks that have undergone changes  (physical or chemical alteration by heat and pressure ). So, they can be formed from changes to an Igneous, Sedimentary, or other Metamorphic Rocks.

All of the following conditions in Earth can cause metamorphic rocks to form except exposure to air. Correct A

Air itself is not enough for the rock to change.