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# A trigonometry problem

Given $\dfrac{\cos A}{\cos B}+\dfrac{\sin A}{\sin B}=-1.$ Then what is the value of $\dfrac{\cos^{3}B}{\cos A}+\dfrac{\sin^{3}B}{\sin A}?$

a ) $$1$$

b ) $$0$$

c ) $$4$$

d ) $$\dfrac{1}{2}$$