**Core Concept**
Morphine is a potent opioid analgesic commonly used for pain management in various clinical settings. Patient-controlled analgesia (PCA) is a method of pain relief where the patient has control over the administration of analgesics, allowing them to administer a predetermined dose at regular intervals or as needed.

**Why the Correct Answer is Right**
In PCA, morphine is administered via an intravenous (IV) pump, which allows the patient to self-administer a bolus dose of the medication. This method provides effective pain control and reduces the risk of opioid-related side effects associated with continuous infusion. The IV route also enables rapid onset of action and precise titration of the dose.

**Why Each Wrong Option is Incorrect**
**Option A:** Intramuscular (IM) injection is not suitable for PCA as it does not provide a consistent and controlled release of the medication.
**Option B:** Subcutaneous (SC) administration is also not ideal for PCA, as it may lead to variable absorption rates and unpredictable pain relief.
**Option C:** Oral administration is not commonly used in PCA, as it may not provide rapid enough pain relief and may be affected by first-pass metabolism.

**Clinical Pearl / High-Yield Fact**
When using PCA with morphine, it is essential to ensure that the patient is adequately monitored for signs of opioid toxicity, such as respiratory depression, and to adjust the dose accordingly.

**Correct Answer: C. Intravenous (IV) pump**