3. Choosing an appropriate FRET pair for a bio-structural experiment takes careful consideration. One parameter that must be considered is the FRET efficiency as a function of the distance between the donor and acceptor fluorophores (r;, ). Shown in Fig. 3 are the FRET efficiencies of two FRET pairs as a function of r,, Which FRET could be applied over a wider range of separations? Explain. C FRET efficiency o ECFP-EYFP pair 10 15 0 1 ros{nm) Figure 38. FRET efficiency vs. donor-acceptor distance for two FRET pairs