Work this out using real rupee numbers from the start, pinned down by the fact that B lost Rs. 200, then check which option matches.
Using total $60x$: beginning shares are T1=12x, J1=15x, B1=33x; ending shares are T2=15x, J2=20x, B2=25x. B's change is $33x - 25x = 8x$, a loss. Since B lost Rs. 200, $8x = 200$, so $x = 25$.
Then J1 = 15(25) = Rs. 375 and J2 = 20(25) = Rs. 500. J's change is $500 - 375 = Rs.\ 125$, a gain. The total money is $60x = 1500$, so J's gain as a fraction of total is $\frac{125}{1500} = \frac{1}{12}$.
Let's summarize:
This confirms option A using concrete rupee values instead of symbolic fractions alone.