Answer:
Option B
Explanation:
Let $P$ = Rs. $x$, $A=3x$, $I$ = Rs. $2x$
$SI$ $=\frac{PNR}{100}$ $\Rightarrow 2x$ $=\frac{x\times R\times 20}{100}$ $\Rightarrow R$ $= 10\%$
In second case :
$P$ = Rs. $x$, $A$ = Rs. $2x$, $I$ = Rs. $x$, $N$ = ?
$SI$ $=\frac{PNR}{100}$ $\Rightarrow 2x$ $=\frac{x\times N\times 10}{100}$ $\Rightarrow N$ = 10 years.