input: Text: DOUBLE TROUBLE by CARL JACOBI Grannie Annie, that waspish science-fiction writer, was in a jam again. What with red-spot fever, talking cockatoos and flagpole trees, I was running in circles—especially since Grannie became twins every now and then. We had left the offices of Interstellar Voice three days ago, Earth time, and now as the immense disc of Jupiter flamed across the sky, entered the outer limits of the Baldric. Grannie Annie strode in the lead, her absurd long-skirted black dress looking as out of place in this desert as the trees. Flagpole trees. They rose straight up like enormous cat-tails, with only a melon-shaped protuberance at the top to show they were a form of vegetation. Everything else was blanketed by the sand and the powerful wind that blew from all quarters. As we reached the first of those trees, Grannie came to a halt. "This is the Baldric all right. If my calculations are right, we've hit it at its narrowest spot." Ezra Karn took a greasy pipe from his lips and spat. "It looks like the rest of this God-forsaken moon," he said, "'ceptin for them sticks." Xartal, the Martian illustrator, said nothing. He was like that, taciturn, speaking only when spoken to. He could be excused this time, however, for this was only our third day on Jupiter's Eighth Moon, and the country was still strange to us. When Annabella C. Flowers, that renowned writer of science fiction, visiphoned me at Crater City, Mars, to meet her here, I had thought she was crazy. But Miss Flowers, known to her friends as Grannie
  Question: What gives away the location of the lens?
  
   (A) When Billy enters the barracks, he realizes he's being hit by Red Fever. 
   (B) Workers were showing their first symptoms from working in the mines. 
   (C) The location was written in the Fever Victims file. 
   (D) Workers were showing their first symptoms after being in the barracks. 
  Answer:
output: Workers were showing their first symptoms after being in the barracks.