"The city is there."
We can use هنالك "hunaalika" as the replacement of هناك "hunaaka" with the same meaning. But, I don't think Duolingo would accept هنالك. Perhaps, you can try to report it if your answer is rejected.
In addition, هنالك can also mean "the city is there (far)" while هناك means "the city is there (near)".