What techniques were used inThe Boarded Window to create the surprise ending

This question is based on the following paragraph. “h, listen! ” said terry. “i can hear her coming down the hallway.” everyone hid behind the couches or in corners. they tried to stifle their giggles and make no sound at all. there was only the sound of a key in the lock as sheila, the birthday girl, came in for the evening. what conclusion can be drawn about what is about to happen? a. terry is playing a game with others. b. sheila is walking into a surprise party. c. terry is stealing some of sheila's belongings. d. sheila is coming home to meet her friends.