Triangle A B C has \angle B A C=60^{\circ}, \angle C B A \leq 90^{\circ}, B C=1, and A C \geq A B. Let H, I, and O be the orthocenter, incenter, and circumcenter of \triangle A B C, respectively. Assume that the area of the pentagon B C O I H is the maximum possible. What is \angle C B A ?
Answer Choices
A. 60^{\circ}
B. 72^{\circ}
C. 75^{\circ}
D. 80^{\circ}
E. 90^{\circ}