Explanation:

- Availability: This refers to having sufficient quantities of food available on a consistent basis. It is a fundamental part of food security, ensuring that there is enough food supply for everyone.

- Accessibility: This means that individuals have adequate resources to obtain appropriate foods for a nutritious diet. It involves having the means to access food through buying, trading, or receiving aid.

- Affordability: This is about the economic ability to buy food. It is important because even if food is available and accessible, it must also be affordable for all individuals.

- Acceptability: This is not traditionally considered a core feature of food security in the basic definition, which focuses more on availability, accessibility, and affordability.

Hence, the correct answer is "Acceptability" as it is often not listed as a primary feature of food security.