Choose the best answer to complete the sentence.In early 2015, prices went up _______ .TungstenHARD LUCKDemand is up, prices have rocketed. The biggest supplier knows why.1. It hardens anything from saw blades to turbine blades. It goes into light bulbs and weaponry. It is tungsten, and its price has gone crazy. Why? China controls 85 % of world output, uses maybe 35-40 of it – and, as demand has risen, has taken steps that cut supply.2. Inside China, prices rose sharply in 2004, by some 70 %. But in 2005 prices rocketed. As the year began, exporters were offering a compound of the metal at around $9,000 a tonne; in March, $19,000; in April, nearly $ 22,000.3. Russia apart, the world has few other potential sources: a large Canadian mine, closed in December 2003 because its customers went off to buy cheaper elsewhere; a smaller Tasmanian one, also idle; one in Portugal; and a few tiny mines here and there. A big opencast mine in Vietnam planned by another Canadian company is likely to come on stream only in late 2007.4. Still, rocketing prices have done one good thing. As it ceased production, North American Tungsten, owner of the closed Canadian mine, has to seek protection from creditors. Today it has settled with them, raised fresh capital, plans soon to reopen its mine and is talking of a second one.