You are writing some code to with the goal of making a visual for the electric field produced from a single charge. As part of the calculation, you need to define a separation vector between the charge and the location at which you will display the electric field. The location at which you'll display the field you've already defined as $r$ obs in the code. The charge has been defined with this line of code:

charge pos $=$vec$(3,2,0),$ radius $=1\mathrm{.}5,$ color$=$color.red$)$

How can you define the separation vector in your code?

$r_{s}ep=r_{o}bs-$ charge $*vec$

$r_{-}$sep $=r_{-}$obs $-$ charge.pos

$r_{s}ep=$vec$($ charge $*$ pos $)-r_{o}bs$

$r_{{?}_{s}ep}=$ charge $*$ pos $-r_{{?}_{o}bs}$

$r_{-}$sep $=$vec$($ charge $)-r_{-}$obs

$r_{s}ep=r_{o}bs-$ vec $(charge.$pos$)$

$r_{-}$sep $=$ charge $*vec-r_{{?}_{o}bs}$

$r_{-}$sep $=r_{-}$obs $-$ vec $($ charge $).$