Choose the correct answer: Post Office service is (1) _______ developing with some certain inventions. 

Fill in each numbered blank with one suitable word or phrase

Post Office service is (1) _______ developing with some certain inventions. The first envelopes were made (2) _________ cloth, animal skins, or vegetable parts. The Babylonians wrapped their messages in thin sheets of clay that were then baked. In 1653, a Frenchman, De Valayer established a postal system in Paris. He set up mail boxes and delivered any letters placed in them if they used envelopes which only he sold. (3) ______ enemy put live mice into the letter boxes and ruined De Valayer's business.

A schoolmaster from England, Rowland Hill (4) ________ the adhesive postage stamp in 1837, an act for (5) _______ he was knighted. Through his efforts the first stamp in the world was issued in England in 1840. Hill created the first uniform postage rates that were based on weight, rather than size.

Post Office service is (1) _______ developing with some certain inventions. 

• A. more
• B. more and more
• C. the more
• D. the most