Concept:The sentence tests the correct phrasal verb used with an alarm to mean it begins to sound suddenly.
Explanation:An alarm "goes off" when it starts ringing or making noise.
This is a fixed expression in English.
"Died off" means gradually became extinct or disappeared.
"Ran off" means fled or left quickly.
"Rang up" means called on the telephone or recorded a sale.
Only "went off" fits the context of a sudden alarm sound.
Therefore, the sentence means everyone was afraid when the alarm started ringing.
Answer:B. went off