FOr which year, the percent increase of foreign exchange reserves over the previous year is the highest ?

Answer: Option D

Explanation:

Before solving this, put a clever eye on the chart, just calculate for those years which are actually having increase if we compare to previous year.
These years are 1992-93, 1994-95, 1996-97, 1997-98

So lets calculate the percentage increase of these years compared to previous years :
\begin{aligned}
\text{i. For year 1992-93 =}\frac{3720-2640}{2640}*100 \\
= 40.91\% \\
\text{ii. For year 1994-95 =}\frac{3360-2520}{2520}*100 \\
= 33.33\% \\
\text{iii. For year 1996-97 =}\frac{4320-3120}{3120}*100 \\
= 38.46\% \\
\text{iv. For year 1997-98 =}\frac{5040-4320}{4320}*100 \\
= 16.67\% \\
\end{aligned}