Which of the following statements is true?

a. The Gartner Group estimates that programming bugs not found until later in the SDLC cost 25% to 30% more to correct than if they had been found earlier in the SDLC.

b. Direct system conversion is the least risky of the system conversion methods.

c. Many software developers state that 5% to 10% of software development costs should be allocated to testing, debugging, and rewriting software.

d. Over the life of a system, only 30% of information systems work takes place during development; the remaining 70% is spent maintaining the system.