Indian Institute of Foreign Trade 2012 Solved Paper

The growth rate of Aluminum from 2006-2010 $=\frac{99-75}{75}\approx 33.33\%$
The growth rate of Coal from 2006-2010 $=\frac{116-88}{88}=28.8\%$
The growth rate of Copper from 2006-2010 $=\frac{97-75}{75}\approx 29.33\%$
The growth rate of Gold from 2006-2010 $=\frac{20-18}{18}\approx 11.11\%$
Thus, Gold witnessed the minimum growth rate in production from 2006 to 2010.
Hence, option D is the correct answer.