Which of these sentences is an oxymoron?

Even though He wanted to travel, Mr. Keynes could not think of any vacation spot as comfortable at his own living room.

Although he didn’t want to, Mr. Keynes took his laptop along with his bathing suit and other holiday clothes because this was a working vacation.

Mr. Keynes was a workaholic who found vacations as relaxing as six rounds of wrestling an alligator.

The island landscape seemed to come alive before Mr. Keynes’ eyes, flora and fauna swimming through his vision in every direction.