So I went through all the answers and could not find the right one amongst. If I'm not wrong the reaction above is the reaction for respiration. The nearest answer is D but unfortunately the first reactant isn't in accordance with that which the question has given.
An isotope has the same number of <em>protons</em> but a different number of <em>elec</em><em>tro</em><em>n</em><em>s</em><em> </em>than others atom of the same element