writersoul-
1) Clearly “It was during the day” is too obvious an answer. Therefore, the correct answer is, the man used to work in the Chernobyl power plant, so he now glows in the dark (boy, that was easy).
2) Same man. The activated charcoal he swallows daily for the radiation absorbed the poison.
3) The Chernobylian man wrote the paragraph. It’s very unusual – how many paragraphs do you know that are written by glow-in-the-dark men?