Which capital structure must consider estimating WACC

Question

Which capital structure must we consider when estimating the WACC for a subsidiary valuation: the one which is reasonable according to the risk of the subsidiary’s business that the average of the company or the one the subsidiary as “tolerates/permits”?

Answer 1

The reasonable one as per to the business risk of the subsidiary, that the average of the company or the one this subsidiary as “tolerates/permits”.