- WHY WAS YOUR LETTER RETURNED

15. - 3500 CAU TRAC NGHIEM ON TAP AV THCS 15. - 3500 CAU TRAC NGHIEM ON TAP AV THCS
3500 CAU TRAC NGHIEM ON TAP AV THCS

15. - Why was your letter returned?

- Because I put only a ... on it.

a. two cents stamps

b. stamp of two cents

c. two-cent stamp

d. stamp two cents

 c