Answer: The best option to answer the question is letter A (bleach)
Explanation:
The question requires us to choose, among the options given, which one corresponds to a chemical compound that is only made by chemists.
Nitrogen (N2) is a gas found in our atmosphere, corresponding to 78% (by volume) in dry air. Therefore, N2 is found in nature.
Water (H2O) is also found in nature, as it is present in our atmosphere, rivers, lakes and oceans (among others).
Copper (Cu) is a metal that is also found in nature, occuring naturally in metal form and being present in minerals.
On the other hand, bleach corresponds to a mixture of chemicals where the main ingredient is sodium hypochlorite.
Therefore, among the options given, bleach is the only one that is made only by chemists (and it is not found as it is in nature).
The best option to answer the question is letter A (bleach).