The Trade Practices Tribunal Described a Market as Having Five

The Trade Practices Tribunal described a market as having five different dimensions that it will consider when determining whether or not that market is competitive.It identified one of these dimensions as being the most crucial.Which is it?

A) The number and size distribution of different sellers and the degree of market concentration.
B) Barriers to entry (i.e.the ease with which new businesses can enter and secure a valuable part of the market) .
C) The existence of extreme product differentiation and promotion.
D) The character of vertical relationships with consumers and suppliers.