Which additional testing methods should the developers employ to prevent an outage?

Dress4win has end to end tests covering 100% of their endpoints.

They want to ensure that the move of cloud does not introduce any new bugs.

Which additional testing methods should the developers employ to prevent an outage?
A . They should run the end to end tests in the cloud staging environment to determine if the code is working as intended.
B. They should enable google stack driver debugger on the application code to show errors in the code
C. They should add additional unit tests and production scale load tests on their cloud staging environment.
D. They should add canary tests so developers can measure how much of an impact the new release causes to latency

Answer: B