Which of the following fixes $CO_2$ in carbohydrates?

Assertion : $C_4$ photosynthetic pathway is more efficient than the $C_3$ pathway.
Reason : Photorespiration is suppressed in $C_4$ plants.

Water is

Which of the following pairs is incorrect?

$A$ student performed an experiment on photosynthesis as follows: They took soda water in a glass tumbler and added chlorophyll to it. They placed the tumbler in sunlight,expecting that they had provided all the necessary components for photosynthesis (i.e.,$CO_2$,$H_2O$,chlorophyll,and light). What do you think will happen after a few hours of exposure to sunlight?

Who proposed the theory of photosynthesis in guard cells?