Which condition would most likely lead to an elevated WBC count?

An elevated white blood cell (WBC) count typically indicates that the body is responding to some form of stress or infection. A viral infection is a prime example because it activates the immune system, causing the body to produce more white blood cells to fight off the invading virus. This increase in WBCs is a direct response to the infection, as lymphocytes, a type of white blood cell, are specifically elevated during viral illnesses to target and eliminate the viral pathogens.

In contrast, dehydration can lead to a relative increase in WBC count due to hemoconcentration, but it does not necessarily indicate an immune response. Anemia involves a decrease in red blood cells or hemoglobin, so it would generally not cause an elevation in WBCs unless there is an underlying infection. Hemoglobinopathy refers to disorders related to the structure of hemoglobin, which primarily affects red blood cells and does not typically influence white blood cell counts. Therefore, a viral infection is the most direct cause of an elevated WBC count among the options provided.