$$\frac{\left(x + \frac{1}{y}\right)^a . \left(x - \frac{1}{y}\right)^b}{\left(y + \frac{1}{x}\right)^a . \left(y - \frac{1}{x}\right)^b} =$$

A

$$\left(\frac{x}{y}\right)^{a + b}$$

B

$$\left(\frac{y}{x}\right)^{a + b}$$

C

$$\left(x + y\right)^{a + b}$$

D

$$\left(x - y\right)^{a - b}$$