In the context of which one of the following are the terms 'pyrolysis and plasma gasification' mentioned?

Answer: (d) Waste-to-energy technologies

Pyrolysis (heat without oxygen) and plasma gasification (very hot plasma) turn waste into fuel oil and syngas.

The idea

Waste can be treated with heat in three ways, and the difference is how much oxygen is supplied. Full oxygen: it burns (incineration). Limited oxygen: it turns into a fuel gas (gasification). No oxygen: it breaks down into oil, gas and char (pyrolysis).

Incineration: full air → heat and ash → Gasification: little air → syngas (carbon monoxide + hydrogen) → Pyrolysis: no air → oil, gas and char → Plasma gasification: electric arc at several thousand °C → syngas and a glassy slag

Why the others are wrong

(c) Hydrogen can be a product, but these are waste treatment methods.

Also know

Indian city waste is wet and mixed, with a lot of kitchen waste, so it burns poorly and several waste-to-energy plants have struggled. Wet waste is better treated by composting or biomethanation, which gives biogas.