**Core Concept**
The given parameters indicate a state of altered acid-base balance, with a low PCO2, high PO2, and alkalotic pH. This suggests a respiratory alkalosis, characterized by **hyperventilation** leading to excessive CO2 elimination.

**Why the Correct Answer is Right**
The low PCO2 (30 mmHg) and high pH (7.45) are indicative of **respiratory alkalosis**. The body attempts to compensate for this imbalance through renal mechanisms, such as increasing H+ ion excretion, but since it's partially compensated, the pH remains alkalotic. The high PO2 (105 mmHg) further supports the diagnosis of respiratory alkalosis due to **hyperventilation**.

**Why Each Wrong Option is Incorrect**
**Option A:** Not provided, assuming it's not the correct answer based on the context.
**Option B:** Not provided, assuming it's not the correct answer based on the context.
**Option C:** Not provided, assuming it's not the correct answer based on the context.
**Option D:** Not provided, assuming it's not the correct answer based on the context.

**Clinical Pearl / High-Yield Fact**
In respiratory alkalosis, the primary disturbance is a decrease in PCO2 due to **hyperventilation**, which can be caused by various factors such as anxiety, panic attacks, or pulmonary embolism.

**Correct Answer:** D. Respiratory Alkalosis