If $r=($:$x,y,z$:$)$ and $r_0=($:$x_0,y_0,z_0$:$),$ describe the set of all points $(x,y,z)$ such that $|r-r_0|=3.$ The set of points is a

circular cylinder with radius $\sqrt[\phantom{2}]{x_0^2{y}_0^2{z}_0^2},$ height $3,$ and axis the $z-$axis

sphere with radius $3$ and center $(x_0,y_0,z_0)$

sphere with radius $9$ and center $(x_0,y_0,z_0)$

sphere with radius $\sqrt[\phantom{2}]{x_0^2{y}_0^2{z}_0^2}$ and center $(0,0,3)$

circular cylinder with radius $3,$ height $|z_0|,$ and axis the $z-$axis