Copper (Cu) reacts with oxygen (O) to form copper oxide (Cu). The properties of copper oxide (CuO) are most likely Different from copper or oxygen
Similar to both copper and oxygen
Similar to only copper
Similar to only oxygen

A- SImilar to both copper and oxygen

Explanation:

If copper and oxygen react to form copper oxide, a compound of both Copper and Oxygen, they most likely have traits from both elements, therefore its A

the old alchemists made significant contributions to science even though there starting premises were off a bit. their conclusions after failure would steer them into better directions for investigation. science is no more than close observation and the initial mistakes result in rethinking and retrying experiments.