Assertion: Cyclic electron flow is the only photosynthetic mode of generating ATP for bundle sheath cells.
Reason: Bundle sheath cells contain PS I but no PS II.

1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.

Both ${\mathrm{C}}_4$ and CAM pathways are regarded as compromises. The reason for this would be:
1. Both pathways lead to reduction of photosynthesis to enable water conservation.
2. To maintain high photosynthetic levels ${\mathrm{C}}_4$ compromises on water loss and CAM compromises on loss of carbon.
3. Both minimize photorespiration and optimize the Calvin cycle.
4. To maintain high photosynthetic levels CAM compromises on water loss and C₄ compromises on loss of carbon.