Answer:
B. an Oligopoly
Step-by-step explanation:
A. monopolistically competitive
This options is not correct because the number os competitors is too small to talk about monopolistic competition.
B: an Oligopoly
This options is correct since market is controlled by just a few competitors.
C. purely competitive
this is wrong because the babysitters are not competing between them.
D. a monopoly
This option is wrong because there is more than one competitor.