If Unit A has not violated the rules, then Unit B cannot be praised. Unit B has been praised, or Unit B's grandson has not been praised. If there is no problem with the audit, then Unit A has not violated the rules. If the above conditions are true, which of the following is true, can we conclude that there is a problem with the audit? ? ['The grandson of Unit B is praised.', 'Unit A did not violate the regulations.', 'Unit B violates regulations.', 'The grandson of Unit B was not praised.']