[A]: Stomata remain open during day
[R]: Stomata help in gaseous exchange.

Options

A. If both A and R are true and R is the correct explanation of A.
B. If both A and R are true but R is not the correct explanation of A.
C. If A is true but R is false
D. A is false but R is true.

Answer

B

Explanation

The opening and closing of stomata is a fucntion of turgor changes in guard cells . In light malic acid produce in guard cells, which dissociates into hydrogen and malate ions, resulting in intake of `K^(+)` ions through `H^(+) -K^(+)` ion exchange . There is increase in concentration of `K^(+)` and malate ions in guard cell, endosmosis of water into guard cells resulting in increased turgor pressure which results in stomatal opening .
Stomata are chiefly concerned with gaseous exchange during photsoynthesis and respiration and water loss through tranpiration.