Final answer:
The characteristic of perfect competition among the options is 'many small buyers and sellers.' High barriers to entry and differentiated products do not align with the definition of perfect competition.
Step-by-step explanation:
The characteristic of perfect competition that matches the options provided is B. many small buyers and sellers. This is because perfect competition is defined by a market structure where there are many sellers as well as many buyers participating in the market, and the products offered by the sellers are identical to each other.
Under perfect competition, there is free entry and exit into the market, meaning there are no high barriers to entry, and products are not differentiated; they are homogeneous. Therefore, both A. high barriers to entry and C. differentiated products are not characteristics of perfect competition.