(None of the four choices) 21​ε0​E2 is the expression of energy density (Energy per unit volume)[21​ε0​E2]=[ L3ML2 T−2​]=[ML−1 T−2]NOTE: From this question, students can take a lesson that in IIT-JEE also questions may be wrong or there may be no correct answer in the given choices. So, don't waste time if you are confident.