Select the true statement(s) about Agile techniques.
a) In Test Driven development, all the tests must be executed only when all the functions have been integrated.
b) Customers are involved in the testing process to help develop acceptance tests for the stories that are implemented.
c) In Extreme Programming, constant refactoring is discouraged as this costs a lot in manpower hours.
d) In test-driven development, if a programmer discovers problems in code developed by someone else, they should refer them back to the original developer who knows the code well.
e) Agile development values processes and tools as they help develop quality software.