Where in a grain can B vitamins and fiber be found?

B vitamins and fiber are primarily found in the bran, which is the outer layer of a grain. The bran is rich in dietary fiber and essential nutrients, including B vitamins, which play crucial roles in metabolism and overall health.

The endosperm, while it contains some nutrients and starch, lacks the high fiber content and the richness in B vitamins that the bran provides. The germ, being the embryo of the grain, is nutrient-dense and contains some B vitamins as well, but it is the bran that is particularly known for its fiber content and is integral to a whole grain's health benefits. Starch, on the other hand, is primarily a carbohydrate found in the endosperm and does not offer significant amounts of vitamins or fiber. Thus, the bran is the component of the grain where B vitamins and fiber are most concentrated and accessible, making it the correct answer.