What is Defense in Depth (DID)? Select one: O a. It is also known as the "Castle Approach" O b. DiD is based on Roman defensive strategies from the 3rd and 4th centuries OC DID defends a system from attack using a number of layered, independent technologies, known as controls Od. It provides redundancy in the event a single security control fails, or a vulnerability is exploited. De All of the above