An important principle of defense in depth is that achieving information security requires a balanced focus on which PRIMARY elements?

Development, testing, and deployment describe phases of a software development lifecycle (SDLC), not the foundational elements of an information security philosophy like defense in depth.

Prevention, detection, and remediation describe phases of an incident response or threat management cycle, which is a subset of security operations rather than the overarching pillars of defense in depth.

Defense in depth as defined by frameworks like NIST and ISC2 explicitly identifies people, technology, and operations as the three primary pillars of a comprehensive security posture. People encompasses training and awareness, technology covers tools and controls, and operations refers to the processes and procedures that tie them together - no single element is sufficient without the others.

Certification, accreditation, and monitoring relate to the risk management and authorization processes used in government frameworks such as NIST RMF, not the primary balanced elements of defense in depth.