Answer: Choice C
[tex]0 \le t \le 42[/tex]
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Explanation:
The domain is the set of all allowed x input values.
In this case, t plays the role as the input, so replace x with t.
The smallest t can get is t = 0
The largest is t = 42, since this is a bit beyond 40 on the horizontal axis.
The value of t can be anything between t = 0 and t = 42, including both endpoints.
Therefore, the domain is [tex]0 \le t \le 42[/tex]