What does the(star) integrity axiom mean in the Biba model? 

Answer options:

A. No read up
B. No write down
C. No read down
D. No write up

D

The(star) integrity axiom of the Biba access control model states that an object at one level of integrity is not permitted to modify an object of a higher level of integrity (no write up). Source: KRUTZ, Ronald L. & VINES, Russel
D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, John Wiley & Sons, 2001, Chapter 5: Security Architectures and Models (page 205).