Answer:
C) f(x) = tan^-1(x)
Step-by-step explanation:
The question is equivalent to asking which trig function passes the horizontal line test over the domain (-90°, 90°). Both the sine function and the tangent function are defined on that domain and pass the horizontal line test.
The inverse sine function has a range of [-90°, 90°] (with square brackets, signifying the end points are part of the range). The inverse tangent function does not have a range that includes ±90°, so is a better match for the range in the question.
