An infant with severe dehydration would be expected to present with:

In cases of severe dehydration, an infant would indeed be expected to present with absent urine output. This is a significant indicator of the body's fluid status. When the body is severely dehydrated, it prioritizes preserving remaining fluids, leading to reduced or absent urine production as the kidneys conserve water. This response is primarily a protective mechanism to maintain blood volume and ensure that vital organs receive sufficient blood flow.

In contrast, excessive tearing would typically indicate adequate hydration, as tears are produced by well-hydrated glands. Moist oral mucosa is also a sign of good hydration; if an infant were severely dehydrated, one would see the opposite: dry mucous membranes. Bulging fontanelles may occur in specific conditions like increased intracranial pressure, but dehydration often results in a sunken appearance instead. Therefore, absent urine output serves as the most critical indicator in this scenario to demonstrate severe dehydration in an infant.