Consider the Three Largest Cell-Phone Service Providers in Canada -

Consider the three largest cell-phone service providers in Canada - Bell,Telus,and Rogers.If we observe that all three companies increase their monthly service fees simultaneously,we might conclude that

A) there is tacit collusion among these firms.
B) these firms have monopolized the industry.
C) they are perfect competitors and they are unable to set the price.
D) they are engaged in predatory pricing.
E) they are creating entry barriers to prevent entry by new firms.