Study the bar graph and answer the question that follows.
The extent of construction of new railway tracks (in km) in four railway sectors A, B, C, D during two consecutive financial years Y1 and Y2 is presented through the given bar graph.

How much is the percentage increase in the railway track length from Y1 to Y2 greater for B than that for D from Y1  and Y2?

A

25

B

100

C

40

D

50