The general reaction between a metal oxide and an acid can be written as:

A

Metal oxide $$+$$ acid $$\rightarrow$$ Salt $$+$$ Water

B

Metal oxide $$+$$ acid $$\rightarrow$$ Salt $$+$$ precipitate

C

Metal oxide $$+$$ acid $$\rightarrow$$ Water $$+$$ gas

D

Metal oxide $$+$$ acid $$\rightarrow$$ Salt $$+$$ gas