The given objective function is \( Z = 5x + 7y \). In this equation, \( Z \) represents the total profit earned by selling \( x \) units of product X and \( y \) units of product Y. Let's analyze the statements:
- The first option suggests the function maximizes the difference of the profit from X and Y. However, the expression \( Z = 5x + 7y \) is not a difference but a sum, indicating combined profits rather than differences.
- The second option implies the function measures total production of X and Y. This interpretation is incorrect because the coefficients 5 and 7 in the function correspond to profit contributions rather than quantities.
- The third option states the function maximizes the combined profit earned from X and Y. This aligns perfectly with the structure of the objective function \( Z = 5x + 7y \) since it sums total earnings, therefore maximizing profits from both products.
- The fourth option indicates that more of X than Y is produced, which is not addressed by the function since it lacks constraints or conditions that enforce the relation between \( x \) and \( y \).
Thus, the correct statement is: The objective function maximizes the combined profit earned from selling X and Y.