In the Center of Porter's Five Forces Model Is Competition

In the center of Porter's Five Forces model is competition.Which of the following represents the four outer boxes?

A) Buyer power, systems power, threat of false entrants, and threat of substitute products or services
B) Buyer power, systems power, threat of new entrants, and threat of substitute products or services
C) Buyer power, supplier power, threat of new entrants, and threat of substitute products or services
D) Business power, supplier power, threat of new entrants, and threat of powerful services