Kyla Corp. monitors performance using return on investment (ROI). The asset values used to compute Kyla's ROI are similar to the values reported on the company's balance sheet, which management finds convenient. However, the calculated ROI is increasing even though the net income has remained steady. Which of the following statements best reflects this situation?

a) Kyla appears to be using the historical cost approach to calculate ROI; the net book value method is more commonly used. b) Kyla appears to be using the net book value approach to calculate ROI; the net realizable value method would provide more stable ROI numbers.

c) Kyla appears to be using the net book value approach to calculate ROI; the historical cost method would provide more stable ROI numbers but has other drawbacks.

d) Kyla appears to be using the net realizable value method to calculate ROI, which is the more commonly used method.