I posted this question already and got the wrong answer (as seen in photo) PLEASE GIVE ME THE RIGHT ANSWER. Thanks

Which of the following could plausibly cause a leftward shift in the marginal efficiency of capital curve, everything else held constant? lower educational attainment lower wages All of the above None of the above The following Figure is from, "From Syringes to Dishes: Improving Food Security through Vaccination," by Erkmen G. Aslim, Wei Fu, Erdal Tekin \& Shipun You, In 28 statn, iridividuals age 65 and older were initially eligible for covid vaccination, while those under age 65 were not. Fikure 4. Elfects of Vaccine Eliglbwity Around the Age Cutof Figure 4. Effects of Vaccine Eligibility Around the Age Cutoff This figure illustrates the method. One example of a factor that could violate the assumption regression discontinuity design (RDD): some other policy is also impacted by the age 65 cutoff This figure lllustrates the method. One example of a factor that could violate the assumption of this method is if regression discontinuity design (RDD ; some other policy is also impacted by the age 65 cutoff and might also reduce food insecunity, such az receiving yoeial seciar instrumental variables (IV); age 65 is directly correlated with covid vaccination, but not food insecurity, difference-in-difference (DiD); food insecurity rates are similar across age