Exp) Option d is the correct answer.

Option d is correct: The exhaust air from Fuel Cell Electric Vehicles (FCEVs) powered by hydrogen consists of pure water vapor.  FCEVs emit only water vapor, making them locally emission-free and contributing to cleaner air in cities.

Source: https://www.thehindu.com/news/national/indianoil-unveils-indias-first-green-hydrogen-run-bus-that-emits-just-water/article67344306.ece

https://indianexpress.com/article/explained/explained-economics/the-problem-with-battery-electric-vehicles-8822335/

https://afdc.energy.gov/vehicles/fuel-cell