Final answer:
Unscheduled telework does not require an announcement by the Director of OPM, but it provides flexibility under closing and dismissal guidelines, is described in the Telework Enhancement Act, and is situational or ad hoc telework.
Step-by-step explanation:
The specific of unscheduled telework that is NOT mentioned is option B, which states that it is announced by the Director of OPM. Unscheduled telework refers to teleworking that is situational or ad hoc, meaning it occurs as needed and not based on a set schedule. This kind of telework provides flexibility in terms of closing and dismissal guidelines, is described in the Telework Enhancement Act, and can be implemented when there is a need for employees to work remotely.