Which among the following is NOT a polyester polymer ?

If $x$, y, z are the sides of a right angled triangle, where z is the largest side, then $\dfrac{1}{\log_{x+z} y} + \dfrac{1}{\log_{z-x} y} =$

If $\omega$ is a complex cube root of unity, then the value of $\sin\left[\pi(\omega^{10} + \omega^{23}) - \dfrac{\pi}{4}\right] =$

If 6 boys and 3 girls are to be seated in a row for a photograph, then the probability that the end seats are occupied by the girls and no two girls are side by side is