**Core Concept**
The child's presentation suggests a severe metabolic acidosis with concomitant respiratory alkalosis due to the loss of bicarbonate-rich fluid through diarrhea and the compensatory hyperventilation. This condition requires prompt treatment to restore acid-base balance and improve peripheral circulation.

**Why the Correct Answer is Right**
The child's metabolic acidosis is best treated with bicarbonate supplementation, but first, the underlying cause of the acidosis must be addressed. In this case, the administration of bicarbonate will help to correct the acid-base imbalance, but it is essential to also replace lost fluids to prevent further dehydration. The correct answer will address both aspects of the child's condition. The use of bicarbonate is crucial in this scenario as it will help to correct the acid-base imbalance by increasing the bicarbonate levels in the blood, thereby reducing the acidity.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not address the underlying cause of the acidosis and only focuses on replacing lost fluids, which is essential but not sufficient in this scenario.
**Option B:** This option is incorrect because it does not provide any treatment for the acid-base imbalance and only focuses on replacing lost fluids.
**Option C:** This option is incorrect because it may worsen the acid-base imbalance by further increasing the respiratory alkalosis, which is already present in this child.

**Clinical Pearl / High-Yield Fact**
In cases of severe metabolic acidosis, it is essential to address the underlying cause of the acidosis and replace lost fluids to prevent further dehydration. Bicarbonate supplementation should be used cautiously and only if the underlying cause of the acidosis has been addressed.

**Correct Answer:** C. Administer intravenous fluids to replace lost fluids and correct dehydration, and give sodium bicarbonate to correct the acid-base imbalance.