Final answer:
Observability, Simplicity, and Stability are characteristic of testable software.
Step-by-step explanation:
All of the above are characteristic of testable software.
Observability refers to the ability to observe and monitor the behavior of the software during its execution to identify any issues or errors. Simplicity means that the software is designed to be straightforward and easy to understand, making it easier to test and identify any bugs or problems. Stability means that the software is reliable and consistent, performing consistently without errors over time.