The Salesperson for BM&M,a Company Manufacturing Automated Sawdust Screens,was Giving

The salesperson for BM&M,a company manufacturing automated sawdust screens,was giving a presentation to a buying agent.During the presentation,the salesperson handed the buyer a letter from a pallet manufacturer in Georgia.The letter praised the efficiency of the BM&M screen and was especially complementary of the fact that the screen only has six moving parts.This letter is an example of a(n) _____.

A) demonstration
B) proposition
C) illustration
D) attestation
E) testimonial