Which of the Following Qualify as Barriers to Entering a Monopoly

Multiple Choice

Which of the following qualify as barriers to entering a monopoly market?
(i) a key resource's ownership is not defined
(ii) the government has given the existing monopoly the exclusive right to produce the good
(iii) the costs of production make a single producer more efficient than a large number of producers

A) (i) and (ii)
B) (ii) and (iii)
C) (i) only
D) (i) , (ii) and (iii)