【单选题】

When Mike Kelly first set out to build his own private space-ferry service, he figures his bread-and-butter business would be lofting satellite into high earth orbit. Now he thinks he may have figured wrong, "People were always asking me when they could go," says Kelly, who runs Kelly Space Technology, "I realized the real market is in space tourism."

According to preliminary market surveys, there are 10,000 would-be space tourists willing to spend $1 million each to visit the final frontier. SpaceAdventures inArlington have taken more than 130 deposits for a two-hour, $98,000 space tour tentatively set to occur by 2005. This may sound great, but there are a few hurdles. Putting a simple satellite into orbit--with no oxygen, life support or return trip necessary--already costs an astronomical $2,200/kg.And that doesn’t include the cost of insuring rich and possibly litigious (爱打官司的) passengers. The entire group of entrepreneurs trying to corner the space- tourism market has between them "just enough money to blow up one rocket".
The U.S. space agency has plenty of money but zero interest in making space less expensive for the little guys. So the little guys are racing to do what the government has failed to do: design a reusable launch system that’s inexpensive, safe and reliable. Kelly Space’s prototype looks like a plane that has sprouted rocket engines. Rotary Rocket inCalifornia has a booster with rotors to make a helicopter-style return to earth. The first passenger countdowns are still years away, but bureaucrats at the FederalAviationAdministration in Washington are already informally discussing flight regulations.After all, you can’t be too prepared for a trip to that galaxy far, far away.
The phrase "bread-and-butter business" ( Line 1, ParA、1 ) most probably means ______.
[A] a business to sell bread and butter[C] the business to make a living
[B] a business to produce bread and butter [D] a traveling agency