A hot cup of coffee is put outside on a cool day. The temperature of the coffee, C in degrees Celsius, is a function of time, t in minutes. Consider the statement C(20)=30. What are the units for 20? 30?

Option C.

Step-by-step explanation:

Consider the below figure attached with this question.

We need to find the input value when f(x)=g(x).

In the given graph red line represents the function f(x) and blue line represents the function g(x).

From the given graph it is cleat that both functions intersect each other at (1.5,1). It means

f(x) = 1 at x=1.5

g(x) = 1 at x=1.5

It means f(x)=g(x)=1 at x=1.5. For input value x=1.5 the statement f(x)=g(x) is true.

Therefore, the correct option is C.