With reference to the role of biofilters in recirculating aquaculture system, consider the following statements :
1. biofilters provide waste treatment by removing uneaten fish feed.
2. biofilters convert ammonia present in fish waste to nitrate.
3 . biofilters increase phosphorus as nutrient for fish in water.
how many of the statements given above are correct?
(a) only one
(b) only two
(c) all three
(d) none.