Answer
$C_{4}$ and CAM plants perform better than $C_{3}$ plants in hot dry places, so one would expect them to increase in abundance in a place where the climate moves in that direction.
Work Step by Step
This question asks you to match up what you know about the biochemical and physiological advantages, under certain conditions, of $C_{4}$ and CAM plants and to predict what would happen to their numbers in the future if certain events happen. How do temperature changes affect photorespiration, and which plants will be most affected by this?