An example:

If Mounted Marauders http://deckbox.org/whi/Mounted%20Marauders attacks a Legend through the Quest zone, and survives combat

does the defending player sacrifice:

A) a support card on the Legend

B) a support or quest card in the Quest zone

C) a card of their choice from either A or B?

A) a support card on the legend is not in any zone, so no

B) yes, this

C) see A