Which of the Following Statements Is True About Porter's Five-Forces

Which of the following statements is true about Porter's five-forces model?

A) The level of threat of entry from competition is generally the same across all industries.
B) Every industry is different in terms of who maintains the power in the firm-supplier relationship.
C) The buyer or customer has no power to force down prices in an industry.
D) Not all companies face the threat of substitutes.