Sentence:  OW: Many see it as the <WSD>Mount Everest</WSD> of tenor roles. What made you feel ready to take it on at this moment in your life? And why with ASO? / RT: It definitely is the <WSD>Mount Everest</WSD> of tenor roles!! 
Meaning of the word marked with <WSD> tags:  Epitome, ultimate; an endeavor that is very demanding yet rewarding.