The higher priority has been given for the use of biogas energy in Nepal, give two reasons.
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Biogas units provide a cleaner and safer source of energy, enabling rural families to produce their own electricity, heat, and fertilizer. One advantage of these plants is that they can be used in exactly the place they're needed, thereby averting the need for extensive, costly power landlines.

if you're asking what comes out, it's steam.

the answer would be a