Which of the following expressions is equal to sin⁡(-150°)?

a. sin(30°)
b. -sin(-30°)
c. -sin(30°)
d. sin(150°)

Check the picture below.

let's notice that the angle -150° has a reference angle of 30°, so any trigonometric function for either angle will be the same value, however, let's recall that the sine or y-coordinate is negative on the III Quadrant, so sin(-150°) is the same as sin(30°) BUT negative, -sin(30°).

-2 is the right