4. Sale of Mathematics and English books in the year 2005, 2006, 2007 and 2008 are given below : Years Mathematics English 2005 200 100 2006 300 250 2007 400 200 2008 500 500 Question 1. In which year is the difference in the sale minimum? (a) 2008 (b) 2007 (c) 2006 (d) 2005 Question 2.