Which of the following is not a quality characteristic listed in ISO 9126 Standard?

The correct answer is supportability, as it is not one of the quality characteristics defined in the ISO 9126 standard. This standard outlines a framework for software quality and includes six main characteristics: functionality, reliability, usability, efficiency, maintainability, and portability.

Functionality refers to the set of features and capabilities that the software provides to fulfill user needs. Usability focuses on how user-friendly and intuitive the software is for users. Maintainability addresses how easily the software can be modified to correct defects, improve performance, or adapt to a changed environment.

Supportability, while it may be relevant in broader discussions of software quality and customer support, is not explicitly defined within the ISO 9126 framework as a quality characteristic. Therefore, this makes supportability the correct answer to the question regarding which option is not part of the ISO 9126 quality characteristics.