Which organism is used for the production of Single Cell Protein $(SCP)$?

Which of the following is true regarding Single Cell Protein $(SCP)$?

The full form of $SCP$ is ..........

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.

Spirulina can be grown easily on....

Statement $P$: Heterotrophic mushrooms are cultivated globally.
Statement $Q$: $A$ cow weighing $250 \, kg$ produces $200 \, g$ of protein per day.