Which of the following might cause hemoglobinuria?

Hemoglobinuria is the presence of hemoglobin in the urine, and it typically occurs when red blood cells are destroyed in the bloodstream, leading to the release of hemoglobin. Trauma can contribute to this condition, particularly when there is significant physical damage to the body, resulting in the rupture of red blood cells or hemolysis. This can be due to conditions such as severe injuries where the blood vessels are compromised, or in cases of massive blood loss or burns.

While excessive hydration might dilute urine, it would not cause hemoglobinuria. A low protein diet could lead to different types of complications but is not directly related to causing hemoglobinuria. High exercise tolerance may lead to other conditions, but it is generally not associated with the release of hemoglobin into the urine unless accompanied by trauma or severe exertion resulting in hemolysis. Thus, trauma is the most directly correlated factor that could cause hemoglobinuria in this context.