The correct option is A 20 tons
A- Single-cell proteins (SCP) are produced by a range of microorganisms and substrate. They are dried cells of microorganism. When SCP is produced, the microbial products produce sufficient proteinaceous substances that can be utilized as protein supplements for animal feeds or human foods. It is estimated that algae grown in ponds can produce 20 tons (dry weight) of protein, per acre, per year.