Answer:
b. √3
Explanation:
Given a point on the unit circle that represents the position of the terminal ray of an angle, the tangent of that angle is the ratio of the y-coordinate to the x-coordinate.
tan(4π/3) = y/x = (-√3/2)/(-1/2) = √3/1
tan(4π/3) = √3
_____
Additional comment
A calculator can confirm this for you.