Final answer:
Glycerin is a by-product of biodiesel production through the transesterification of vegetable oil, where it's formed alongside the main product, biodiesel.
Step-by-step explanation:
True. Glycerin, or glycerol, is indeed a by-product of the production of biodiesel via transesterification of vegetable oil. During this chemical process, a triglyceride reacts with an alcohol (commonly methanol) to form an ester, which is the biodiesel, and glycerol. Since biodiesel is typically made from plant oils like soybean or rapeseed oil, the glycerin obtained can be used in various applications, including skin lotions, cosmetics, and even in the production of nitroglycerin, which is used in dynamite. This means that glycerol is a co-product of the production of biodiesel, rather than a by-product.