Which of the following findings is expected in a child with congestive heart failure?

In children with congestive heart failure, exercise intolerance is a key finding due to the heart's decreased ability to effectively pump blood and meet the body's increased demands during physical activity. This leads to fatigue and a reduced capacity for exertion, making it difficult for the child to keep up with peers or engage in normal activities without experiencing shortness of breath or excessive tiredness. The heart's impaired function can result in a backlog of blood, contributing to symptoms like decreased exercise tolerance.

The other findings in the options do not align with the typical manifestations of congestive heart failure. For example, heart sounds such as S1 and S2 are expected in all healthy hearts, while bradypnea, or slow breathing, is not typical; instead, tachypnea (increased respiratory rate) is often seen due to the heart's inability to supply adequate oxygen to the body. Additionally, in congestive heart failure, neck veins are typically distended rather than flattened, indicating increased pressure in the venous system due to heart dysfunction.