Which statement most accurately distinguishes dietary fiber from functional fiber?

Dietary fiber is always composed of cellulose and lignin and cannot be used industrially, whereas functional fiber refers to any man-made carbohydrate designed to mimic fiber in structure and promote health outcomes despite being chemically distinct from natural fibers.

Dietary fiber is fiber that has been enriched back into a refined grain product, while functional fiber is the fiber that remains in whole grains and cannot be removed by processing.

Dietary fiber refers to fibers found only in grains and cereals, while functional fiber refers only to fibers that come from fruits and vegetables but are concentrated into supplements or extracted form and then added to foods.

Dietary fiber is present naturally in foods; functional fiber is isolated or extracted and added to foods.