Zinc phosphide, zn3p2, is often used as a rat poison. phosphorus has 5 valence electrons. how many valence electrons does each zinc atom lose?

The choices that should have accompanied this question were:
A. 1 
B. 2 
C. 3 
D. 4 

My answer is B. 2.
Below is an explanation, I found while doing the research.

Phosphate needs 3 electrons each totaling 6 electrons so each zinc will need to give up 2 electrons.

Phosphate wants to imitate the electron configuration of Argon because noble configurations are the most stable. With P getting the extra electrons the valence shell will be 3s2 3p6, which is the same as Argon. Without the extra electrons, the P valence shell looks like this 3s2 3p3, now you can see why each phosphorus wants 3 more electrons, that will make it 3s2 3p6, just like Argon.