The researchers developed an assay to measure ABCA1-mediated cholesterol efflux to apolipoprotein A-I (apoA-I). In this assay, different concentrations of lipid-free apoA-I were added (at time 0) to membranes expressing ABCA1 or ABCA1/APOE. Cholesterol fluorescence, which is enhanced when high concentrations of intracellular cholesterol are present to bind to the filipin dye complex, was measured over time.

Based on the data in figure 1 which of the following conditions has the highest level of ABCA1-mediated cholesterol efflux?