What is Single Cell Protein $(SCP)$?

Spirulina is a

People recovering from a long illness are often advised to include the alga $Spirulina$ in their diet because it

Given below are two statements with respect to single cell protein.
Statement $I$: Single cell protein refers to the crude,or refined edible protein,extracted from pure microbial cultures or from dead or dried cell biomass.
Statement $II$: $SCP$ can be readily used as fodder for achieving fattening of calves,pigs,in breeding fish and in poultry.
In the light of the above statements,choose the correct answer from the options given below.

Which of the following is an algal source of $SCP$?

Which bacterium has the capacity to produce $25$ tonnes of protein due to its high rate of biomass production and growth?