Answer
$IV$
Work Step by Step
Given that $r(u,v)=ucosvi+usinvj+vk$
To find the grid curves corresponding to $u$ as constant , substitute $u=k$
$r(k,v)=kcosvi+ksinvj+vk$
This is an equation of helix with circular orbits and constant radius $=k$
Only plot $IV$ and $V$ contain grid curves which are helix.
But only plot $IV$ contains helical grid curves with constant radius.
