Okay, here we have this:
Considering that if θ is any angle, then θ + n(360) is coterminal angle with θ, for all nonzero integer n. Let's check one by one:
Option A:
180°-90°=90°
They are not coterminal angles because the difference between them is different from a multiple of 360°.
Option B:
550°-190°=360°
190°-(-10°)=200°
They are not coterminal angles either because the difference between them (200°) is different from a multiple of 360 °.
Option C:
120°-(-1200°)=1320°
They are not coterminal angles either because the difference between them (1320°) is different from a multiple of 360 °.
Option D:
710°-350°=360°
350°-(-730°)=1080°/360°=3
They are coterminal angles because the difference between them is equal to a multiple of 360 °
Finally we obtain that the correct answer is the option D.