**Core Concept**
Hypoperfusion refers to a state of inadequate blood flow to tissues and organs, often resulting from decreased cardiac output, hypotension, or impaired vascular tone. It can lead to tissue hypoxia, organ dysfunction, and ultimately, multi-organ failure.

**Why the Correct Answer is Right**
Hypoperfusion is characterized by a decrease in the delivery of oxygen and nutrients to tissues, which can be assessed through various clinical and laboratory parameters. One key indicator of hypoperfusion is a decreased capillary refill time (CRT), which is the time it takes for capillary blood flow to return after applying gentle pressure to the skin. A CRT of more than 2-3 seconds is often considered abnormal and indicative of hypoperfusion.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because a normal blood pressure reading does not necessarily indicate hypoperfusion. Patients with hypoperfusion may have normal blood pressure, especially if they have a compensatory increase in cardiac output.

**Option B:** This option is incorrect because a normal pulse oximetry reading does not necessarily indicate adequate tissue oxygenation. Pulse oximetry measures oxygen saturation in arterial blood, not tissue oxygenation.

**Option C:** This option is incorrect because a normal urine output does not necessarily indicate adequate renal perfusion. Patients with hypoperfusion may have normal urine output initially, but eventually, they may develop oliguria or anuria.

**Clinical Pearl / High-Yield Fact**
Remember that hypoperfusion can occur in the absence of hypotension, especially in patients with cardiac dysfunction or vasodilatory shock. Always assess capillary refill time and other clinical parameters in addition to vital signs to evaluate tissue perfusion.

**Correct Answer:** C. Decreased capillary refill time.