Which organism is useful for producing a chemical that inhibits immunity during organ transplantation?

Assertion: Vitamin $B_2$ is found in cereals,green vegetables,brewer's yeast,egg white,milk,and liver.
Reason: It can be commercially produced by some yeasts.

How many of the following microorganisms are bacteria?
Aspergillus niger,Acetobacter aceti,Clostridium butylicum,Lactobacillus,Brewer's yeast,Baker's yeast,Propionibacterium shermanii,Penicillium notatum

Which one of the following has been commercialised as a blood-cholesterol lowering agent?

Which of the following is not an antibiotic?

$A$ brewery subjects about $1$ tonne of purified jaggery to fermentation under ideal conditions. If it has produced $0.3$ tonne of alcohol, what quantity of $CO_2$ has it expelled into the atmosphere (in $tonne$)?