$S$ - Statement: Heterotrophic mushrooms are cultivated globally.
$R$ - Reason: $A$ $250 \ kg$ cow produces $200 \ kg$ of protein daily.

Consider the following four statements $(1-4)$ and select the option that includes all the correct statements:
$(1)$ The unicellular $Spirulina$ can produce large quantities of food rich in protein,minerals,vitamins,etc.
$(2)$ $Methylophilus$ $methylotrophus$,because of its high rate of biomass production and growth,can produce $25$ tonnes of protein per day.
$(3)$ Common button mushrooms are rich in Vitamin $C$.
$(4)$ Rice varieties have been developed which are rich in calcium.

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 of food rich in protein,minerals,vitamins,etc.
$(B)$ Body weight-wise,the microorganism $Methylophilus$ $methylotrophus$ may be able to produce several times more proteins than the cows 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.

Which of the following statements is incorrect regarding the use of Single Cell Protein $(SCP)$?

Single Cell Protein $(SCP)$ is obtained through which process?

What is $Spirulina$?