If ax = b, by = c and cz = a, then the value of xyz is = ?

Answer: Option B

$$\begin{array}{rl}& a^1\\ & =c^z\\ & ={\left(b^y\right)}^z\\ & =b^{yz}\\ & ={\left(a^x\right)}^{yz}\\ & =a^{xyz}\\ & \Rightarrow xyz=1\end{array}$$