question:  Why are there hidden microphones?
context: When you try to get a job, they ask to see your ID before they even tell you if there's an opening or not. If your CPA ID says you're a DCT, you're SOL and they tell you there's no openings. I've been a garbage man, street-cleaner, ditch-digger—" On the other side of the room, the jukebox came to life with a roar and a group of teen-agers scrambled to the dance floor. Feeling safe from hidden microphones because of the uproar, he leaned across the table and whispered in the girl's ear, "That's what I want to hire you for. A civilization weary of murder, robbery, kidnapping, counterfeiting, blackmail, rape, arson, and drunkenness had originated the CPA—Crime Prevention Association. There were no longer any prisons—CPA officials had declared loudly and emphatically that their job was to prevent crime, not punish it. Instead, he was sent to a hospital where all criminal tendencies were removed from his mind by psychologists, shock treatments, encephalographic devices, a form of prefrontal lobotomy and a dozen other methods. The CPA system was, actually, cheaper than previous methods because it did away with the damage caused by countless crimes; did away with prisons and their guards, large police forces, squad cars and weapons. He was a hero to the millions of men and women who had suppressed impulses to kill someone, beat their mates, get drunk, or kick a dog. A crime because it theoretically inflicted psychological injury upon the intended victim—and because millions of women voters had voted it a crime. On the other hand, attempted murder, robbery, kidnapping, etc., were not crimes. It would be hard not to recognize: the room was large, devoid of furniture except for a desk and chairs, but the walls were lined with the controls of television screens, electronic calculators and a hundred other machines that formed New York's mechanical police force. We have a lot of microphones hidden in a lot of alleys.
output:  The hidden microphones are there to detect criminal activity, so the CPA can stop it before it starts.
options:  The hidden microphones are there because the girl is an FBI agent, looking to take down a mafia boss.  The hidden microphones are there to make sure the bartender keeps the drinks watered down.  The hidden microphones are there to detect criminal activity, so the CPA can stop it before it starts.  The hidden microphones are there as part of a drug sting.