Recall the Application About the Merger of Sirius Satellite Radio

Recall the Application about the merger of Sirius Satellite Radio and XM Satellite Radio to answer the following question(s) .
-Recall the Application. One might expect no more firms to enter after the market consolidated into one firm because

A) the fixed cost of setting up a company system and acquiring programing is very high.
B) the marginal cost of adding addition subscribers if very high.
C) demand is very elastic.
D) all of the above.