Technician A says the zinc phosphate

 coating is nearly an airtight coating over the

 bare metal surface. Technician B says the

 zinc phosphate coating must be covered

 with a topcoat in order to preserve its

 corrosion-protecting capabilities. Who is

 correct?

 A)Technician A only

 B)Technician B only

 C) Both Technicians A and B

 D) Neither Technician A nor B

Please find Explanation 

Step-by-step explanation

Answer:-  Zinc phosphate coating is a part of conversion coating. This is a second step involved in preventing corrosion after preparing the surface. After etching and conversion coating using zinc phosphate, a layer of air tight protective surface gets created on the metal piece.

Thus, tech A is correct.

             A topcoat is applied to the zinc phosphate, so that the layer of phosphate does not go away so quickly. This topcoat also helps zinc phosphate in retaining the corrosion capabilities.

Thus, tech B is correct.

Thus, the correct option is C.