Developing a safety$-$critical software system is more time consuming and expensive than developing a non$-$safety$-$critical but high$-$quality system because it requires extreme measures for identifying and removing defects; a great deal of effort to identify and mitigate risks; and

a$.$ a division of responsibilities between software developers and systems engineers

b$.$ a totally different sequence of software development tasks

c$.$ a development team composed of highly trained and experienced professionals

d$.$ an end product that is easy to learn and use, performs well, and meets users' needs