30. What makes red become thethe best colour choice for sleeping night light?
A Biological cycles in our own brains.
B. The invention of electrical light.
CThe traditional attitude to red
D. The rising of the sun in the morning
31. What is the best title for the text?
A. Is green light good for sleep?
B. A night light in bedroom: yes or no?
C. What color of night light helps you sleep best?
D. What kind of light helps babies sleep?