Given that C(w) represents the cost in dollars, of a sundae weighing 'w' ounces.
Here the cost is a function of the weight of yogurt sundaes.
The variable 'w' acts as the independent variable and 'C' acts as the dependent variable.
The domain of the function is defined as the smallest set of all possible values that the independent variable can take.
Since the weight cannot be negative, it follows that,
And note that the weights can be fractional as well. It means 'w' is not restricted to integral values and can also take rational values.
Therefore, the domain of the function will be the set of non-negative rational numbers.
So, the 4th option is the correct choice.