I drew an imaginary line passing through point O and forming two right triangles, as seen in the attached image.
The angles at O must all add up to 180, so:
60 - b + 90 - b + a = 180
Combine like terms:
150 - 2b + a = 180
Add 2b to both sides:
150 + a = 180 + 2b
Subtract 180:
a - 30 = 2b
Okay, now what is this equation telling us? Well, if we start with a and make it smaller by 30, then it will be equal to twice b. We can see, then, that a must be much greater than b, making the answer E, a > b.
Attachments

In the figure, lines l and k are parallel. If a is an acut.png [ 14.51 KiB | Viewed 5315 times ]