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

The correct answer identifies "Supportability" as a quality characteristic that is not included in the ISO 9126 standard. The ISO 9126 Standard outlines six primary quality characteristics that are essential for assessing software quality: Functionality, Usability, Reliability, Efficiency, Maintainability, and Portability.

Functionality refers to the features and capabilities of the software that fulfill specified requirements. Usability focuses on how easy and intuitive the software is for users to interact with. Maintainability addresses how easily the software can be modified to fix defects, improve performance, or adapt to changes in the environment.

Supportability, while it might refer to the ease with which software can be supported or maintained, is not one of the designated characteristics in ISO 9126. This standard primarily addresses different dimensions of quality that are critical for user satisfaction and operational effectiveness of the software product. Thus, recognizing the correct attributes outlined by the ISO standard is key to understanding software quality assurance.