Choice A rationale:

Vital signs are crucial to assess the child's overall condition and the severity of gastroenteritis. Elevated heart rate and decreased blood pressure may indicate dehydration.

Choice B rationale:

Travel history is important to identify potential sources of infection or exposure, which can help determine appropriate treatment and infection control measures.

Choice C rationale:

Urinary output can be monitored to assess the child's hydration status. Decreased urine output may indicate dehydration.

Choice D rationale:

Blood glucose level, while relevant in some medical conditions, is not a primary consideration in the assessment of gastroenteritis.

Choice E rationale:

Skin turgor reflects the degree of dehydration. Poor skin turgor may indicate significant fluid loss.