Let 100 be the value in 2008. In 2009 it will become 100×1.18 In 2010 it will become 100×1.18×1.18 In 2011 it will become 100×1.18×1.18×0.88 In 2012 it will become 100×1.18×1.18×0.88×1.18≈145 thus, the effect =45% Hence, option C is the correct answer.