What Is the Rule of Thumb Behind Porter's Five Forces

What is the rule of thumb behind Porter's five forces model?

A) The stronger the five forces, the greater the industry's profit potential-making the industry less attractive.
B) The stronger the five forces, the lower the industry's profit potential-making the industry more attractive.
C) The weaker the five forces, the greater the industry's profit potential-making the industry more attractive.
D) The weaker the five forces, the lower the industry's profit potential-making the industry less attractive.