The rate of health complications of patients on intravenous (IV) therapy at a particular hospital was higher than usual. Government inspectors found that the typical IV solutions used in this hospital had somewhat high concentrations of sodium and potassium, which were raising patients' blood pressure and taxing their kidneys. The government inspectors mandated lowering the sodium and potassium in these IV preparations, and threatened with a possible government fine. In compliance, the hospital lowered the sodium and potassium levels in the IV solutions to the correct levels. Nevertheless, patients on IV therapy at that hospital continued to have a high rate of health complications.Which of the following, if true, most helps to explain why acting on the government inspectors' recommendations failed to achieve its goal?
【选项】A high proportion of patients at this hospital are older, and older patients are more vulnerable to infections that can accompany IVs.