In the structure given below, how many heteroatoms are present?

Hetero atoms in an organic compound are referred to as atoms other than hydrogen and oxygen present. In the given structure oxygen atom as the only hetero atom present. Thus only one hetero atom is in this molecule. Heteroatoms are atoms that are not carbon or hydrogen but have been inserted in the place of carbon or hydrogen in a molecular structure. These atoms will either attract electrons more or less than the carbon atom. Polarity characterizes the bond that exists between the heteroatom and the carbon atom. The reactivity of the organic molecule is impacted by heteroatoms. Oxygen, nitrogen, bromine, chlorine, sulfur, phosphorus, iodine, lithium, and magnesium are a few examples of heteroatoms.

Hence, option A is correct.