Fuel cell, using hydrogen and oxygen as fuels, A. has been used in spaceship B. has as efficiency of \(40%\) to produce …

A. has been used in spaceship ✅
Yes, hydrogen–oxygen fuel cells were used in Apollo missions.

B. has an efficiency of 40% to produce electricity ✅
Fuel cells typically have efficiencies around 40–60%; 40% is acceptable.

C. uses aluminium as catalysts ❌
Catalyst used is platinum (Pt), not aluminium.

D. is eco-friendly ✅
Product is water, so it is environmentally friendly.

E. is actually a type of Galvanic cell only ✅
Fuel cell is a galvanic (voltaic) cell producing electrical energy from a spontaneous redox reaction.

Correct option: 🔹 D