Considering the available options, the optimal capital structure has been achieved when the "Debt-equity ratio selected results in the lowest possible weighted average cost of capital."
The primary purpose of the optimal capital structure is how a company upholds the perfect balance between maximizing the wealth and value of the company while at the same time reducing capital cost.
Optimal capital structure is a term that describes the proportionality of a company structure in terms of equity and debt.
Hence, in this case, it is concluded that the correct answer is "Debt-equity ratio selected results in the lowest possible weighted average cost of capital."
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