We know that in Calvin cycle for fixation of one CO2 molecule, 3 ATP and 2 NADPH are required.
So so for fixation of one glucose molecule, 18 ATP and 12 NADPH are required.
In this question they asked for two molecules of sucrose. And 2 sucrose molecules are equivalent to 4 molecules of glucose.
Thus, 72 ATP and 48 NADPH should be used.
Then why is option given as number 1?

Dear Student,

Ans. 120 ATP and 48 NADPH

C4  pathway  guarantees only carboxylase activity of Rubisco, to avoid losses due to photorespiration ( oxygenase activity of Rubisco). C4 pathway contains additional steps so, have extra energy requirement also. C4 pathway requires 30 molecules of ATP (12 additional ATP), whereas C3 pathway requires only 18 of ATP for the synthesis of one molecule of glucose.

Sucrose contains one molecule of glucose and one molecule of fructose. Therefore for one molecule of sucrose 60 ATP are required and for two molecule of sucrose 120 ATPs are required.

Now, in order synthesize one molecule of glucose in C4 plants, 30 ATP and 12 NADPH 
will be required. 
Similarly, for the formation of one molecules of  sucrose it requires 24 NADPH. So, for the synthesis of two molecules of sucrose, 48 NADPH will be required. 



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