For which year were the domestic sales of automobiles closest to the average (2004-2008) domestic sales of automobiles?

Total domestic sales of automobiles in the year 2004 = (700+450+300) = 1450

Total domestic sales of automobiles in the year  2005 = (675+500+350) = 1525

Total domestic sales of automobiles in the year  2006 = (900+625+400) = 1925

Total domestic sales of automobiles in the year  2007 = (1050+600+375) = 2025

Total domestic sales of automobiles in the year  2008 = (975+550+350) = 1875

Average domestic sales of automobiles for the given period = $$\dfrac{1450+1525+1925+2025+1875}{5}$$ = 1760.

Hence, we can say that the domestic sales in the year 2008 is the closest to the average domestic sales. Hence, option D is the correct answer.