This Question Contains Two Parts; Be Sure to Answer Both

This question contains two parts; be sure to answer both.
First, what is the grapevine, and when does the grapevine flourish and thrive?
Second, suppose that you manage a small laboratory that develops fragrances (men's colognes, women's perfumes, unisex deodorants). The office grapevine is thriving; employees believe that the company is about to be purchased by a much larger firm, and that the result will be a move to another state, decreased benefits, and massive layoffs. While the company is under negotiations to be purchased, there will be no move or change in benefits based on the purchase. Layoffs could occur, but it's hard to say at this point. Describe several ways that you might get the grapevine under control.