23.Which of the following statements is correct regarding internal control?

a. A well-designed internal control environment ensures the absolute achievement of an entity's control objectives.

b. An inherent limitation to internal control is the fact that controls can be circumvented by management override.

c. A well-designed and operated internal control environment should detect collusion perpetrated by two people.

d. Internal control is a necessary business function and should be designed and operated to detect all errors and fraud.