Which of the Following Best Defines Heuristics

Which of the following best defines heuristics?

A) They are data charts that evaluate an output variable over a range of values for two different input variables.
B) They are sets of values that are saved and substituted automatically on the worksheet.
C) They are limitations,requirements,or other restrictions that are imposed on any solution.
D) They are solution procedures that generally find good solutions without guarantees of finding an optimal solution.