Solution
Option 1 -> Incorrect because capital structure is not about the relationship between debt and earnings; earnings are income statement items, not financing sources.
Option 2 -> Partially correct but incomplete; retained earnings are only one component of equity, and capital structure encompasses total equity, not just retained earnings.
Option 3 -> Incorrect because earnings represent profitability, not a source of financing; capital structure deals with how a company funds its operations.
Option 4 -> Correct definition; capital structure represents the proportion of debt and equity used by a company to finance its assets and operations.
Hence, Option 4: It indicates a mix between debt and equity -> Capital structure is a fundamental concept in corporate finance that refers to the way a company finances its overall operations and growth by using different sources of funds, primarily consisting of debt (bonds, loans) and equity (common stock, preferred stock, retained earnings). This mix determines the company's financial leverage and risk profile. -> correct