BONUS QUESTION: Name an airline that operated not three but four different types of four engine narrow bodied jetliners - but NOT all at the same time.
Not counting the Trident 3E,
American: BAe 146, 707, 720, Convair 990
MEA: VC10, 707, 720, Comet
There aren't many 4 engine narrow bodies. I can think of these: 707, 720, DC-8, Convair 880, Convair 990, Comet, Concorde, VC-10, BAe 146, IL-62, Tu-144.