If $$sin (A+B)= cos (A + B)$$, what is the value of tan A?

A

$$\frac{1-cosec \ B}{1+ cosec \ B}$$

B

$$\frac{1+tan \ B}{1-tan \ B}$$

C

$$\frac{1+sec \ B}{1-sec \ B}$$

D

$$\frac{1-tan \ B}{1+tan \ B}$$