Given a text T, and several options, according to the question posed in the text T to choose the most appropriate option from the options as the answer, please directly output the most appropriate option, do not need to output the explanation.

According to the static trade-off theory:
Option A:debt should be used only as a last resort.
Option B:companies have an optimal level of debt.
Option C:the capital structure decision is irrelevant.

Answer: B