**Core Concept**
Capnography is a crucial monitoring technique in anesthesia that provides real-time information about the partial pressure of carbon dioxide (CO2) in the respiratory gases. It is used to confirm proper endotracheal tube placement and to monitor ventilation.

**Why the Correct Answer is Right**
Capnography is the fastest and most accurate method to confirm intubation because it measures the CO2 levels in the exhaled breath, which are directly related to the respiratory function. The presence of a CO2 waveform on the capnograph indicates that the endotracheal tube is correctly placed in the trachea, beyond the vocal cords. This is because CO2 is produced by the metabolism of cells in the body and is transported to the lungs via the bloodstream, where it is exhaled. The characteristic "capnogram" waveform, which consists of a rapid rise and fall of CO2 levels, is seen when the tube is in the correct position.

**Why Each Wrong Option is Incorrect**
**Option B:** Clinically by auscultation is subjective and may not always confirm correct tube placement, as breath sounds can be misleading, especially in infants with respiratory distress.

**Option C:** Chest radiography, although a definitive method, is time-consuming and may not be immediately available, making it less ideal for rapid confirmation of intubation.

**Option D:** Airway pressure measurement can indicate the presence of an air leak, but it does not confirm correct tube placement, as it may still be present with an incorrectly placed tube.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that a normal capnogram waveform should have a rapid rise time, a peak CO2 level of 35-45 mmHg, and a rapid decay time. This indicates correct tube placement and proper ventilation.

**✓ Correct Answer: A. Capnography**