(25)7.5 × (5)2.5 ÷ (125)1.5 = 5?

Answer: Option B

$$\begin{array}{rl}& \text{Let}{\left(25\right)}^{7.5}\times {\left(5\right)}^{2.5}÷{\left(125\right)}^{1.5}=5^x\\ & \text{Then},\frac{{\left(5^2\right)}^{7.5}\times {\left(5\right)}^{2.5}}{{\left(5^3\right)}^{1.5}}=5^x\\ & \Rightarrow \frac{5^{\left(2\times 7.5\right)}\times 5^{2.5}}{5^{\left(3\times 1.5\right)}}=5^x\\ & \Rightarrow \frac{5^{15}\times 5^{2.5}}{5^{4.5}}=5^x\\ & \Rightarrow 5^x=5^{\left(15+2.5-4.5\right)}\\ & \Rightarrow 5^x=5^{13}\\ & \therefore x=13\end{array}$$