Answer: Option 'A' is correct.
Step-by-step explanation:
Chemical precipitation means obtain a solid substance from a solution which is separable.
It can be done in two ways :
1) by converting substance into insoluble form.
2) by changing the composition of solvent to reduce the solubility.
Salt is formed by chemical precipitation.
When two solutions which contains salt are combined together, then precipitation occurs due to which insoluble salt is formed.
Hence, option 'A' is correct.