I mostly believe in between D and B beacuse K3po4 and caco3 is not an element equation
Answer:

Explanation:
The molecular formula of the monohydrate formed = 
The molecular mass of the monohydrate formed = 
So, Mass = 24 + 14 + 6 × 1 + 5 × 16 = 155 g
Mass of phosphorus = 31 g
Thus,

Number of Carbon atoms = 3*1 + 1 = 3 + 1 = 4
In short, Your Answer would be Option B
Hope this helps!