Answer: Thursday December 18
Step-by-step explanation:
The ex date for regular way trades will be set at Thursday December 18. The ex date for regular way trades is typically set a day before the record date.
In this case, we are told that the corporation declares a cash dividend on Friday, December 5th, which was payable to the holders of record on Friday, December 19th.
Since the record date is the question is Friday, December 19th, then the ex date for the regular way trades will be set at Thursday December 18 which is a day before the 19th.