Please answer the following question: Answer the following question given this paragraph: Vegetable oils are being explored for a variety of uses in which they could replace petroleum products. One such application is in the field of lubricants. Every moving part in machinery (such as engine pistons) needs lubrication to decrease friction and prolong the life of the equipment. Petroleum products serve this purpose now, but are not good for the environment. New techniques for making specialized esters from vegetable oil are being explored that will make the compounds more stable and more useful as lubricants. Q: What type of oil is being explored to replace petroleum products in lubricants? Choices: - essential oil - diesel - whale oil - vegetable A:
Answer:
vegetable