Which best describes the simple security rule?

A.
No write up in the Biba model

B.
No read down in the Biba model

C.
No write down in the Bell-LaPadula model

D.
No read up in the Bell-LaPadula model

Explanation:
D: The simple security rule is implemented to ensure that any subject at a lower security level cannot view data that resides at a higher level. The reason this type of rule is put into place is to protect the confidentiality of the data that resides at the higher level. This rule is used in the Bell-LaPadula model. Remember that if you see simple in a rule, it pertains to reading, while * or star pertains to writing.