This question is incomplete because the options are missing. Here are the options:
A graph
A diagram
A mathematical function
The best tool to build an economic model to predict the revenue from the sale is a mathematical function.
A mathematical function is a term to refer to the relationship between two variables, characterized by the relationship in which the value of the first variable depends on the second variable.
Additionally, a mathematical function allows to predict or have a result from the relationship of different variables. In this case the variables would be "sales of the pies", "price of the pies" and "price of the pies in other stores" that allow knowing the revenue produced by the sale of the pies.
According to the above, the correct answer is C. because it is the necessary tool to predict the revenue that Sydney will obtain from different variables.
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