a)	When the customer or client requirements clear then 
that time use the waterfall model
j)	QA is the verification-developers
k)	QC is the validate-test
l)	UAT is the client


My name is k.chandra sekhar,
My phone no are 9246540049 65880049, Hyderabad.
My mail id is ndra_143@yahoo.co.in 
I am taking the class for projects and interview trips if 
you interest contact