Given:
The graph of a function.
To find:
The range of the function.
Solution:
Range is the set of y-values or output values.
From the given graph it is clear that,
[tex]f(x)\to -\infty\text{ as }x\to -\infty[/tex]
[tex]f(x)\to \infty\text{ as }x\to \infty[/tex]
And the value function can be any real number. So,
Range = [tex]-\infty<y<\infty[/tex]
Range = [tex](-\infty, \infty)[/tex]
Range = y is all real numbers.
Therefore, the correct option is D.