Final answer:
The angle that has its terminal side on the positive y-axis is π/2 radians.
Step-by-step explanation:
The angle that has its terminal side on the positive y-axis is a) π/2 radians.
To visualize this, imagine a coordinate plane where the x-axis is horizontal and the y-axis is vertical. The positive y-axis is the vertical line above the origin (0,0). An angle of π/2 radians or 90 degrees will have its terminal side pointing directly upwards towards the positive y-axis.