If a$\xi\;b$ are two positive integers,x is their AM and $y\;\xi\;z$ are two GMs then calculate the value of $\frac{y^3+z^3}{xyz}$

Question

$(a)\;\frac{ab^3+a^3b}{abx}\qquad(b)\;2\qquad(c)\;\frac{a^3+b^3}{3ab}\qquad(d)\;\frac{x^3+y^3}{xyz}$