Answer:
The only one that makes sense IF the model behaves as the Earth is D.
Explanation:
B I got it right
I think its 1.40M Na^+ we convert to Na3PO4 which means we need 1.40M x (1 mole Na3PO4/3 mol Na^+) = 1.40 x 1/3 = 0.467 M Na3PO4.