Beholder 2

After you have accomplished the series of tasks to earn Soap Opera and/or DOKA 2 and have left the hidden room, return to DeSalvo's office and ask what he wants. He will ask you to push a paper cart (which has now appeared in his office) into the shredder. After you complete this task (ignoring or saving the man in the cart), several days later, you will be summoned to see DeSalvo in his office on your way into work. Agree to work with Albert, then head right to the shredder area and talk to the Stranger who yells near the shredder. Spend 900 Authority to lure him into DeSalvo's office, talk to DeSalvo about the victim, then watch the cutscenes. Choose Refuse.

Head right, up to DeSalvo's office, search his desk and take the remote. Return downstairs to the left and interact with the podium. Choose to save the child to earn the trophy. You can earn both this and Simple Math by making a save before interacting with the podium.