Final answer:
The net operating income increased by approximately 41.27%.
The correct answer is none of all.
Step-by-step explanation:
To calculate the percentage increase in net operating income, we need to find the change in income and divide it by the original income. In this case, the change in income is $13,000 (38,000 - 25,000) and the original income is $31,500 ((38,000 + 25,000) / 2).
Percentage change = (13,000 / 31,500) × 100 ≈ 41.27%
Therefore, the net operating income increased by approximately 41.27%.