**Core Concept:**
Pulmonary embolism (PE) is a life-threatening condition characterized by the presence of a blood clot in one of the pulmonary arteries, leading to impaired pulmonary gas exchange and potentially respiratory failure. The diagnosis of PE requires a high index of suspicion as clinical presentation can be non-specific.

**Why the Correct Answer is Right:**
The correct answer, D-Venous Thrombophlebitis (VTE) work-up, is a comprehensive diagnostic approach that includes clinical suspicion, risk assessment, and appropriate imaging studies to confirm the presence of a deep vein thrombosis (DVT) and pulmonary embolism. It is crucial to identify the underlying risk factors and evaluate for clinical signs and symptoms, including shortness of breath, chest pain, hemoptysis, and elevated D-dimer levels. If DVT is suspected, compression ultrasonography (USG) is the initial imaging modality to confirm its presence. If DVT is confirmed, further assessment for PE is warranted.

**Why Each Wrong Option is Incorrect:**
A. Pulmonary angiography: Although invasive and invasive procedure, it is the gold standard for confirming the diagnosis of PE, it is not routinely performed due to its invasiveness and high risk of complications.
B. Computed tomography pulmonary angiography (CTPA): Although a non-invasive modality, it exposes the patient to ionizing radiation which carries a small risk of cancer induction.
C. Ventilation-perfusion scan (V/Q scan): This nuclear medicine test has limitations, including the need for ionizing radiation, complexity, and the possibility of false-negative results in patients with large emboli.

**Clinical Pearl:**
A high index of suspicion, combined with a thorough clinical assessment and appropriate investigations, is essential to diagnose PE. In clinical practice, D-Venous Thrombophlebitis (VTE) work-up is the standard approach, involving risk assessment, clinical evaluation, and appropriate imaging studies for DVT and PE confirmation. While CTPA and V/Q scan are useful tools, they come with potential risks. Pulmonary angiography is rarely used due to its invasiveness, while V/Q scan has limitations.

**Correct Answer:** D-Venous Thrombophlebitis (VTE) work-up