A red one is concerning
I believe the answer is:
alert
(Other definitions for alert that I've seen before include "Thinking and acting quickly" , "In state of watchfulness" , "Wide awake and watchful" , "On the ball" , "Lively" .)
I believe the answer is:
alert
(Other definitions for alert that I've seen before include "Thinking and acting quickly" , "In state of watchfulness" , "Wide awake and watchful" , "On the ball" , "Lively" .)