Which of these are the key tenets of Agile?

A$.$ Continuous quality control, Detailed risk planning, Release planning, Flexibility.

B$.$ Stage based development, Detailed planning, Timeboxing, Flexibility.

C$.$ People$-$centric, iterative and incremental, self$-$organized and customer collaboration.

D$.$ Timeboxing, Frequent Feedback, Collaboration with stakeholders and Infrequent integration.