Which of the following is a sign of breathing difficulty in children?

In assessing signs of breathing difficulty in children, the correct choice highlights an important physical response to respiratory distress. Increased respiratory effort is a clear indicator that a child may be struggling to breathe. When a child experiences difficulty in breathing, they may exhibit signs such as rapid and labored breathing, use of accessory muscles, or changes in their breathing pattern. This physiological response is the body's way of trying to compensate for inadequate oxygenation or increased work of breathing.

The other choices, while they may relate to different aspects of a child's health, do not directly indicate breathing difficulty. An increase in body temperature can point towards infection or other medical issues but is not specific to respiratory distress. A decrease in pulse rate might suggest a more severe situation, such as impending cardiac arrest or shock, rather than directly indicating respiratory issues. Lastly, altered mental status can occur due to hypoxia or other systemic problems, but it is also a broader sign that does not exclusively indicate breathing difficulty.

Hence, the significance of increased respiratory effort as a direct observation of a child's struggle with breathing makes it the most accurate indicator in this context.