Consider the following materials:

1. Agricultural residues
2. Corn grain
3. Wastewater treatment sludge
4. Wood mill waste Which of the above can be used as feedstock for producing Sustainable Aviation Fuel?

Sustainable Aviation Fuel (SAF) is a liquid fuel used in commercial aviation that reduces CO2 emissions by up to 80%.

SAF can be produced from various feedstocks, including:

• Waste oils and fats
• Green and municipal waste
• Non-food crops
• Corn Grain
• Oil seeds
• Algae
• Other fats, oils, and greases
• Agricultural residues
• Forestry residues
• Wood mill waste
• Municipal solid waste streams
• Wet wastes (manures, wastewater treatment sludge)
• Dedicated energy crops

It is estimated that the United States can sustainably collect 1 billion dry tons of biomass annually, sufficient to produce 50-60 billion gallons of low-carbon biofuels.

Since all the given materials (Agricultural residues, Corn grain, Wastewater treatment sludge, and Wood mill waste) are listed as potential feedstocks, they can be used for producing Sustainable Aviation Fuel.

Therefore, option c is the correct answer.