trade deficit = excess of imports over exports
trade deficit = import - export
if trade deficit = (export)*(1/5) , we got the year
2000,2001,2002 can't be answer, bcz import < export
now check 2003 onwards
2003 : trade deficit = 70-60=10
(export)*(1/5) = 60/5=12
10!=12 it's not the year
2004 : trade deficit = 80-70=10
(export)*(1/5) = 70/5=14
10!=14. it's not the year
2005 : trade deficit = 90-70=20
(export)*(1/5) = 70/5=14
10!=14 it's not the year
2006 : trade deficit = 120-100=20
(export)*(1/5) = 100/5=20
20 = 20 it's the YEAR
2007 : trade deficit = 120-110=10
(export)*(1/5) = 110/5=22
10!=22 it's not the year
So, Answer D