Which of the following is a sign of sensory processing difficulties in children?

Extreme reactions to sensory input are indeed a hallmark sign of sensory processing difficulties in children. This can manifest as heightened sensitivity or unexpected emotional responses to commonplace stimuli, such as loud noises, bright lights, or certain textures. Children with these difficulties may become easily overwhelmed, reacting with distress, anxiety, or difficulty self-regulating in response to experiences that others might find tolerable or even unnoticeable.

In contrast, signs like a calm demeanor in new situations, a preference for quiet environments, and quick adaptability to changes in routine may indicate typical or even positive coping mechanisms rather than difficulties with sensory processing. Each of these traits often reflects a child's ability to handle their environment effectively, whether through comfort in new situations, management of sensory input, or flexibility in response to change. Therefore, the presence of extreme reactions clearly highlights challenges in processing sensory information, making it the correct choice in this context.