Answer:
Option A. Add one green candy
Step-by-step explanation:
From the question given above, the following data were obtained:
Red color => Proton
Green => Neutron
Blue => Electron
Isotopy is a phenomenon where by two or more elements have the same atomic number by different mass number due to the difference in the neutron number. The atoms involved are called isotopes.
From the above definition, isotope exist when the neutron number of the atoms are different with each having same atomic number (i.e proton number).
Thus, considering the question and the options given above, the only way to make a different isotope of oxygen is to add a green candy (i.e neutron).