单选题 Official market-moving announcements of this kind are frequently foreshadowed by unofficial rumours. Buying or selling on the basis of such "inside" information violates the rules of most stock-markets, but is widely practised and hard to document. Sometimes a rumour may be spread deliberately for the purpose of artificially raising a share price, usually by investors who hold shares which they want to sell. This is the so-called "ramp".The word "ramp" in the paragraph is closest in meaning to ______