This is an axial chest CT image (appears to be at the level of the aortic arch/superior mediastinum). Based on the anatomical positions of the labeled structures:

Structure 1 — Ascending Aorta (anterior, right-sided round vascular structure in the mediastinum)

Structure 2 — Superior Vena Cava (SVC) (anterior, slightly right of midline — the question confirms option 2 at 52% is correct per the green highlight)

Structure 3 — Descending Aorta (posterior, left paravertebral round structure)

Structure 4 — Right Lung / Pulmonary vessels on the right side (lateral structure)

However, given the answer choices visible at the bottom and the green highlight on option 2, the standard NEET PG 2024 answer for this question is:

The partially visible answer options at the bottom of the screen (1. A... 2. S... 3. D... 4. Trachea) align with:

On a standard axial CT chest at the level of the aortic arch, these four structures are classic landmarks used in radiological anatomy teaching.