Operating profit in 1991-92 = Rs. 160 lakh
Operating profit in 1990-91 = Rs. 130 lakh
\[
\text{% Increase} = \frac{160 - 130}{130} \times 100 = \frac{30}{130} \times 100 \approx 23.08%
\]
Rounding to the nearest option given, it matches most closely to 23%, but if precise rounding is avoided, actual increase is ~23.1%. However, considering typical exam rounding to nearest whole number, this should be 23%.
If the question considers exact values, answer: 23%.