question:  Why did Morgan turn on the lights at Infield & Morgan when Reggie entered?
context: Henry Infield placed the insulated circlet on his head gently. The gleaming rod extended above his head about a foot, the wires from it leading down into his collar, along his spine and finally out his pants leg to a short metallic strap that dragged on the floor. The people we treat are on one side of the line and we're on the other. Floating before him in memory was the vertical hoop and the horizontal hoop, both of shining steel-impervium alloy. The gyro actually passed over a man's shoulder, through his legs, under his arms. Any time he felt the walls creeping in to crush him, he could withdraw his head and limbs into the circle and feel safe. Infield stepped into the main stream of human traffic and tried to adjust to the second change in the air. Many "Cures" were not readily apparent. A young man with black glasses and a radar headset (a photophobe) was unable to keep from being pushed against Infield. It was the first time in years that anyone had apologized to Infield for anything. A clean-cut young man with mouse-colored hair was moving toward the stubble-chinned, heavy-shouldered man quivering in the center of a web of impervium cables stuck secure to the walls and windows of buildings facing the street, the sidewalk, a mailbox, the lamp post and Infield. Mouse-hair yelled hoarsely, "Uncouple it, Davies! The magnetic suction dart dropped away from Infield like a thing that had been alive and now was killed. Mouse-hair drove a fast, hard right into the soft blue flesh of Davies' chin. "Not—not long," Infield evaded. Infield's pulse raced, trying to get ahead of his thoughts, and losing out. Infield shifted around, trying to see that side of his benefactor, but couldn't manage it in good grace. This was revealed, as he turned his head, to be a small metal cube above his left ear.
output:  Because he was sensitive to sound, Morgan's Cure was wearing ear protection. So he had to turn on the lights in order to read Reggie's lips.
options:  The room was too dark, and he wanted to see who had entered his business so suddenly in the middle of a bad storm.  He wanted to surprise Reggie with his presence so that he could dismantle Reggie's Cure easier.  Because he was sensitive to sound, Morgan's Cure was wearing ear protection. So he had to turn on the lights in order to read Reggie's lips.  In his shock at the news of Infield's death, Morgan turned on the light so that he could see Reggie and make sure he was telling him the truth.