Assertion : The atmospheric concentration of $CO_2$ at which photosynthesis just compensates for respiration is referred to as $CO_2$ compensation point.
Reason : The $CO_2$ compensation point is reached when the amount of $CO_2$ uptake is less than that generated through respiration because the level of $CO_2$ in the atmosphere is more than that required for achieving $CO_2$ compensation point.

• A
  If both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.
• B
  If both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.
• C
  If the Assertion is correct but Reason is incorrect.
• D
  If both the Assertion and Reason are incorrect.