Answer:
a) an interior optimum (firm value maximizing) debt ratio
Step-by-step explanation:
Trade off Theory is about capital structure of an economic unit. It mentions about the benefit of debt - ie tax saving, as interest on debt is tax deductible; & cost of debt - bankruptcy & insolvency risk, due to fix interest cost.
The theory depicts the debt level, which is best to - balance interest tax shield against the costs of financial distress imply, which implies that it seeks a balance between benefit & cost of debt.
So, the theory finds the best interior optimum (firm value maximising) debt equity ratio.