OK, Let's isolate p-chloroaniline* from the solution which contains it.
An acidic aqueous solution contains the salt* of p-chloroaniline, p-chloroanilinium hydrochloride*.
You want to change p-chloroaniline hydrochloride (salt of an organic base*) to the water-insoluble p-chloroaniline (organic base) by converting the salt to a non-protonated* form.
Which solution will you add?