A child with Tetralogy of Fallot has clubbed fingers. This is a sign of:

Correct option is A

Clubbing results from chronic hypoxia due to poor oxygenation, which is common in cyanotic congenital heart diseases like Tetralogy of Fallot. Explanation of options:
· (a) ✔ Long-standing hypoxia leads to clubbing.
· (b) ✘ Hypertension doesn't cause clubbing.
· (c) ✘ May occur but doesn't cause clubbing.
· (d) ✘ Not related to clubbing in heart disease.