Propose an efficient synthesis for the following transformation:
The transformation above can be performed with some reagent or combination of the reagents listed below. Give the necessary reagents in the correct order, as a string of letters (without spaces or punctuation, such as "EBF"). If there is more than one correct solution, provide just one answer.
A. HBr
B. NaOEt
C. 1) $R_2BH$, 2) $H_2O_2$, NaOH
D. NBS, heat
E. conc. $H_2SO_4$, heat
F. $H_2SO_4$, $H_2O$, $HgSO_4$
