The Alternative Pathways of Photosynthesis Using the C4 or CAM

The alternative pathways of photosynthesis using the C4 or CAM systems are said to be compromises. Why?

A) Each one minimizes both water loss and rate of photosynthesis.
B) C4 compromises on water loss and CAM compromises on photorespiration.
C) Both minimize photorespiration but expend more ATP during carbon fixation.
D) CAM plants allow more water loss, whereas C4 plants allow less CO2 into the plant.
E) C4 plants allow less water loss but CAM plants allow more water loss.