Answer: Maintenance capital expenditures exclusively.

**Explanation:** Depreciation expense serves as a reliable proxy for estimating maintenance capital expenditures, as it reflects management's assessment of the cost associated with fixed assets expensed on the income statement, aligning with their usage. In contrast, growth capital expenditures are more discretionary, driven by management's expansion strategies and revenue growth projections, making depreciation expense an unsuitable basis for forecasting such expenditures. Thus, option B is correct.

Author: LeetQuiz Editorial Team