Assignment#$121.$ Why do we need to do software maintenance?

a$)$ Improve the design

b$)$ Correct faults

C$)$ Restrict software accessd$)$ Migrate and retire legacy software

$2.$ When do we start doing software maintenance?

a$)$ Early during user requirements phase

b$)$ During development of software

c$)$ After the software has been deployed$/$installed

$3.$ The document "Waterfall vs Agile vs Scrum" criticizes haevily these techniques. On the other hand, these techniques are still alive as Project Management Techniques.Searching on the Internet will give you an idea what is going on$.$ Please write a short report on your findings.