The correct option is C the 'data are inadequate', i.e. from the facts given you cannot say whether the inference is likely to be true or false
Here, no conclusive inference can be drawn out as the data given are insufficient. The passage mentions that there was a slowdown in the world economy post- September 11. However, it does not state what was the economic trend before September 11. The data given regarding cotton acreage in India and the yarn industry also does not provide enough information to help conclude that the world economy witnessed an upward trend pre-September 11.