Before their merger, XM and Sirius were competing sellers in the U.S. satellite radio market. The ...

Before their merger, XM and Sirius were competing sellers in the U.S. satellite radio market.  The U.S. Department of Justice allowed the merger even though it created a single seller in the market.  Why might we expect this merger to have limited impact on U.S. consumers?
A) There are many close substitutes for satellite radio service (e.g., free AM-FM radio, internet radio)
B) The merged firm is likely to act on behalf of its customers and keep its prices and profits low
C) U.S. consumers are known to have perfectly inelastic demand for satellite radio (i.e., they are unresponsive to price changes)
D) all of the above are correct