参考答案：B

解析：During the first 48 to 72 hours of fluid resuscitation therapy, hourly urine output is the most accessible and generally reliable indicator of adequate fluid replacement. Fluid volume is also assessed by monitoring mental status, vital signs, peripheral perfusion, and body weight. Pulmonary artery end-diastolic pressure (PAEDP) and even central venous pressure (CVP) are preferred guides to fluid administration, but urine output is best when PAEDP or CVP are not used. After the first 48 to 72 hours, urine output is a less-reliable guide to fluid needs. The victim enters the diuretic phase as edema reabsorption occurs, and urine output increases dramatically.