In which of the following years, the difference between the productions of Companies X and Y was the maximum among the given years ?

Answer: Option D

Explanation:

Although if we have deep look on line chart the nwe can judge that it was in year 2000
Lets also solve it,

For 1997 = (139000 - 119000) = 20000
For 1998 = (120000 - 99000) = 21000
For 1999 = (141000 - 100000) = 41000
For 2000 = (128000 - 78000) = 50000
For 2001 = (120000 - 107000) = 13000
For 2002 = (159000 - 148000) = 11000

Clearly the difference was maximum in year 2000.