In the following question, some of the words in the passage have been left out. Read the passage carefully and choose the correct answer to each question out of the four alternatives and fill in the blanks.
The REM (Rapid Eye Movement) cycle is a sleep stage (1)_____ by rapid eye movements, low muscle tone throughout the body, and vivid dreaming. It is a deeply fascinating stage of our sleep that plays a (2)_____ role in brain development and mental health. During a normal night, our body cycles through different sleep stages every ninety minutes. REM sleep is the final stage of this cycle, occurring mostly in the early morning hours. It gets its name because our eyes rapidly dart back and forth behind our closed eyelids, signalling (3)_____ brain activity. To protect us from physically acting out these wild dreams and hurting ourselves, our brain temporarily (4)_____ our major muscles. This temporary lockdown is called muscle atonia. Neurologists view the REM cycle as the brain's ultimate overnight cleanup crew; it (5)_____ our daily emotions, sharpens our memory, and stores everything we learned during the day.
What should come in blank 2?
Show answer & explanation
Correct answer: B
Explanation
Correct Answer: Crucial
Explanation
• The sentence highlights how vital REM sleep is for essential bodily functions such as brain development and mental health.
• The adjective crucial means extremely important or decisive. It naturally forms the standard collocation "plays a crucial role".
• Words like minor (unimportant) and optional (not compulsory) contradict the positive and essential tone established in the passage, while sudden does not make sense in this context.