Answer: Option (3) is the correct answer.
Step-by-step explanation:
A precipitate is defined as an insoluble solid formed when two aqueous solutions chemically combine to each other.
For example,

Since, it is known that (aq) represents aqueous and (s) represents solid. So, in this reaction barium sulphate (
) is the insoluble solid.
Hence,
is the precipitate that is formed.
Thus, we can conclude that in the given reaction
substance is the precipitate.