The given graph represents the rainfall (in cm) in a city, over a period of six years. Study the graph and answer the question that follows.

In which two consecutive years was the difference of the rainfall minimum?

From the graph,

Difference of rainfall of the two consecutive years 2005 - 2006 = |50 - 40| = 10

Difference of rainfall of the two consecutive years 2006 - 2007 = |100 - 50| = 50

Difference of rainfall of the two consecutive years 2007 - 2008 = |80 - 100| = 20

Difference of rainfall of the two consecutive years 2008 - 2009 = |20 - 80| = 60

$$\therefore\ $$The difference of rainfall is minimum in the consecutive years 2005 - 2006

Hence, the correct answer is Option D