C. all real numbers
Real numbers include ALL Rational and Irrational numbers. These include negatives, square roots, decimals, and positives, etc.
The range of a function is the set of possible output values, which are graphed on the vertical y-axis. Here in this graph, we see it extends beyond the 10 unit markers on each axis. The range is (-infinity, infinity) because there is no restriction on x. The range is a set of all real numbers. Also written as negative infinity < y < positive infinity.
Any x value (input) will give a corresponding y value (output). The graph’s set of y values appear to have no lower and upper limits since no values are excluded and the straight line continues. Thus it confirms that the range of the graphed function is all real numbers.
Hope this helps!