C-02-Q167mediumsingle_mcq
If Secchi disk can be seen at more than 30 cm depth, it means —
If Secchi disk can be seen at more than 30 cm depth, it means —
- aPlenty of food
- bLow amount of food
- cToxic water
- dOptimum pH
If Secchi disk can be seen at more than 30 cm depth, it means —