The Sunland Company has an after$-$tax cost of debt capital of $4$ percent, a cost of preferred stock of $7$ percent, a cost of equity capital of $10$ percent, and a weighted average cost of capital of $6$ percent. Sunland intends to maintain its current capital structure as it raises additional capital. In making its capital$-$budgeting decisions for the average$-$risk project, the relevant cost of capital is:

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