Explanation:

Recently, the Indian government has invited public comments for introducing adoption of E20 fuel to promote green fuel like ethanol.

• Composition: E20 fuel is a blend of 20% of ethanol with gasoline.
• The current permissible level of blending is 10% of ethanol, though India reached only 5.6% of blending in 2019.
• Green fuel, also known as Biofuel, is a type of fuel distilled from plants and animal materials, believed by some to be more environmentally friendly than the widely-used fossil fuels that power most of the world. Some of the biofuels are:

Bioethanol

• It is derived from corn and sugarcane using the fermentation process.
• A litre of ethanol contains approximately two thirds of the energy provided by a litre of petrol.

Biobutanol

• It is produced in the same way as bioethanol i.e. through the fermentation of starch.
• The energy content in butanol is the highest among the other gasoline alternatives. It can be added to diesel to reduce emissions. 

Biohydrogen

• Biohydrogen, like biogas, can be produced using a number of processes such as pyrolysis, gasification or biological fermentation.
• It can be the perfect alternative for fossil fuel.

Hence only statements 2&3 are correct.