If $cosec^2 θ(cosθ-1)(1+cosθ) = k$, then what is the value of k?

1 -1 $\frac{1}{2}$ 0

-1

cosec²θ ( cosθ - 1) ( 1 + cosθ ) = k cosec²θ ( cos²θ - 1) = k { we know,  sin²θ + cos²θ = 1 } cosec²θ ( - sin²θ ) = k -1 =  k