Which of the following statements is not correct? (a) The complexity of a DAC model represented in matrix format with n

[answerhappygod]

Which of the following statements is not
correct?
(a) The complexity of a DAC model represented in matrix format
with n users and m resources is O(mn)
(b) Environmental attributes are used for authentication
purposes in both ABAC and RBAC models
(c) Although the set of roles in RBAC models is supposed to be
static, one can implement some levels of dynamism using a family of
RBAC models working together
(d) Authentication using memory cards is vulnerable to physical
loss of the token