Consider the following four statements (a-d) and select the option which includes all the correct ones only.
(a) Single cell Spirulina can produce large quantities food rich in protein, minerals, vitamins etc.
(b) Body weight-wise the microorganisms Methylophilus methylotrophus may be able to produce several times more proteins, than the cow per day.
(c) Common button mushrooms are a very rich source of vitamin C.
(d) A rice variety has been developed, which is very rich in Calcium.

Spirulina is a cyanobacterium, that can be consumed by humans and other animals. It is used as a dietary supplement as well as a whole food and is rich in proteins, vitamins, minerals etc.It has been calculated that a 250 kg cow produces 200 g of protein per day. In the same period, 250 gm of a micro-organism like Methylophilus, methylotrophus, because of its high rate of biomass production and growth, can be expected to produce 25 tonnes of proteins.Common button mushrooms are a very rich source of B-vitamins (not vitamin C).Rice is rich in starch (carbohydrates).Thus, the correct answer is option C.