input: Text: My Lady Greensleeves By FREDERIK POHL Illustrated by GAUGHAN This guard smelled trouble and it could be counted on to come—for a nose for trouble was one of the many talents bred here! I His name was Liam O'Leary and there was something stinking in his nostrils. It was the smell of trouble. He hadn't found what the trouble was yet, but he would. That was his business. He was a captain of guards in Estates-General Correctional Institution—better known to its inmates as the Jug—and if he hadn't been able to detect the scent of trouble brewing a cell-block away, he would never have survived to reach his captaincy. And her name, he saw, was Sue-Ann Bradley, Detainee No. WFA-656R. He frowned at the rap sheet, trying to figure out what got a girl like her into a place like this. And, what was more important, why she couldn't adjust herself to it, now that she was in. He demanded: "Why wouldn't you mop out your cell?" The girl lifted her head angrily and took a step forward. The block guard, Sodaro, growled warningly: "Watch it, auntie!" O'Leary shook his head. "Let her talk, Sodaro." It said in the Civil Service Guide to Prison Administration : "Detainees will be permitted to speak in their own behalf in disciplinary proceedings." And O'Leary was a man who lived by the book. She burst out: "I never got a chance! That old witch Mathias never told me I was supposed to mop up. She banged on the door and said, 'Slush up, sister!' And then, ten minutes later, she called the guards and told them I refused to mop." The block guard guffawe
  Question: What are the tangler fields?
  
   (A) a type of uniform meant to keep the inmates secure
   (B) electronic fields in Block O that identify inmates
   (C) replacement for guards in Block O
   (D) electronic fields near the floor to stop prisoners
  Answer:
output: electronic fields near the floor to stop prisoners