Answer:
oxalate, fluoride, carbonate, phosphate.
Step-by-step explanation:
It is important to consult the solubility chart in order to determine the anions.
Any compound with a low Ksp means the compound is very insoluble.
Hence, it means the formation of this compound is favoured strongly and its dissolution which would liberate calcium ions is unfavoured.
Any compound with a low Ksp would therefore "soak up" all the free calcium and will thus not be present in the solution.
Using solubility chart and noting the compounds with a low Ksp value, the anions that are probably present are: oxalate, fluoride, carbonate, phosphate.