∆ OPM is an isosceles triangle and PS̅̅̅̅ bisects ∠OPM, the measure of ∆OPS is congruent to the measure of ∆MPS, if the measure of ∆MPS is 200, what is the measure of ∆OPS?

a. 100
b. 200
c. 300
d. 400​