Assertion : Under conditions of high light intensity and limited $\mathrm{CO}_2$ supply, photorespiration…
Assertion : Under conditions of high light intensity and limited $\mathrm{CO}_2$ supply, photorespiration has a useful role in protecting the plants from photo-oxidative damage.
Reason : If enough $\mathrm{CO}_2$ is not available to utilize light energy for carboxylation to proceed, the excess energy may not cause damage to plants.
If both assertion and reason are true and reason is the correct explanation of the assertion
If both assertion and reason are true but reason is not the correct explanation of the assertion
If assertion is true, but reason is false
Both assertion and reason are false statements.
Solution
Photorespiration protects the plants from photoxidative damage by dissipating excess of excitation energy. When the $\mathrm{CO}_2$ supply is limited and under high light intensity photorespiration takes place thus protecting the plants. If enough $\mathrm{CO}_2$ is not available to utilize light energy for carboxylation to proced, the excess energy will cause photoxidative damage to the plants. The energy liberated should be used in photophosphorylation in presence of $\mathrm{CO}_2$. If $\mathrm{CO}_2$ is less then in $\mathrm{C}_3$ plants $\mathrm{O}_2$ combines with $\mathrm{RuBP}$ to form phosphoglycollate thus utilizing the excess energy.