Read the following letters and choose the best one from the given answers for the missing prepositions. Dear Sirs, Iron Nails We are interested (1) buying large quantities of Iron Nails of all sizes and would be thankful if you could give us a quotation per metric ton CIF Lagos, Nigeria. It would also be appreciated if samples and/or a brochure could be forwarded to us. We used to purchase this article from other sources but we now prefer to buy from your corporation because we are given (2) understand that you are able to supply larger quantities (3) more attractive prices. Besides, we have confidence (4) the quality of Chinese products. We look forward to hearing from you (5) return. Yours sincerely,