Cereal straw is a particularly rich source of

Answer: Option B

Straw is an agricultural byproduct consisting of dry stalks of cereal plants after the grain and chaff have been removed. It has several different uses, including fuel, livestock bedding, fodder, thatching and basket making.
Straw may be fed as part of the roughage component of the diet to cattle or horses. It has a low digestible energy and nutrient content. It is a particularly rich source of Potash.