The number of common tangent to the two circles $x^2+y^2-8x+2y=0$ and $x^2+y^2-2x-16y+25=0$ is :

Question

$$\begin {array} {1 1} (a)\;1 & \quad (b)\;2 \\ (c)\;3 & \quad (d)\;4 \end {array}$$