There are over a dozen security models in the CISSP exam.
Bell-LaPadula. Biba. Clark-Wilson. Brewer-Nash. Take-Grant.
Most candidates try to memorize all of them.
There is a simpler way.
Two questions answer almost every security model scenario on the exam:
What does this model protect - confidentiality or integrity?
Who controls the access rules - the user or the system?
Answer those two questions and the right model becomes obvious.