question:  What was special or impressive about Gertrude?
context: The Blue Behemoth By LEIGH BRACKETT Shannon's Imperial Circus was a jinxed space-carny leased for a mysterious tour of the inner worlds. With Shannon's Imperial Circus, the Greatest Show in Space, plastered so thick with attachments...." I've wet-nursed Shannon's Imperial Circus around the Triangle for eleven years, and I know. It's lousy, it's mangy, it's broken-down! I had plenty of time to think how I only weigh one-thirty-seven to Shannon's one-seventy-five, and how I'm not as young as I used to be. It has always been my desire to lighten the burden of life for those less fortunate...." He went on, quietly, "I have always held that entertainment, of the right sort, is the most valuable aid humanity can have in its search for the alleviation of toil and boredom...." "There are many towns along the Venusian frontiers where no entertainment of the— proper sort has been available. It was Gow, our zoo-man—a big, ugly son-of-a-gun from a Terran colony on Mercury. Gow looks a lot like the scenery—scowling, unapproachable, and tough. His hands, holding the curtains apart, had thick black hair on them and were not much larger than the hams of a Venusian swamp-rhino. He said, "Boss, Gertrude's actin' up again." "Gertrude be blowed," growled Bucky. "I'm tellin' you, Boss, Gertrude ain't happy. Beamish cleared his throat and said, rather stiffly, "Gertrude?" "She's the star attraction of our show, Mr. Beamish. The only other one on the Triangle belongs to Savitt Brothers, and she's much smaller than Gertrude." Gertrude may be a little creaky, but she's still pretty impressive. I only hoped she wouldn't die on us, because without her we'd have a sicker-looking circus than even I could stand. The extreme rarity of the animal...."
output:  She was an extreme rarity.
options:  Her outrageous temperment  She was an extreme rarity.  Her extraordinary size and young age  She was exceptionally talented