Final answer:
The fundamental tenet of information security that ensures information is accessible to authorized persons when needed is known as 'Availability'. Among the main objectives of information security, Availability, alongside Confidentiality and Integrity, plays a critical role in safeguarding information systems.
Step-by-step explanation:
The question asked is about a fundamental tenet of information security which ensures that information must be accessible to authorized persons when required for their job functions. The correct option for this principle is b) Availability. Information security is based on three main objectives, often called the CIA triad: Confidentiality, Integrity, and Availability. Confidentiality assures that information is accessible only to those authorized to have access. Integrity involves maintaining the consistency, accuracy, and trustworthiness of data over its entire lifecycle. However, Availability ensures that authorized users have access to information and associated assets when required. Availability is crucial for business continuity and for the overall reliability of information systems.
Additionally, the review question provided (which does not pertain to the primary question) asks which one is not among the four pillars of food security. The four accepted pillars of food security are Availability, Access, Utilization, and Stability. Therefore, option D, Transformation, is not one of the four pillars of food security.