Explanation (A): in ‘TRN’ is coded as USO. U Comes After T, S comes After R, and O comes After N.
so likewise
in ‘USA’, V comes after U, T comes after S, and B comes after A.
then ‘USA’ will be coded as ‘VTB’.
Explanation (B): in ‘APE’ is coded as ‘BQF’. B Comes After A, Q comes After P, and F comes After E.
so likewise
in ‘CAT’, D comes after C, B comes after A, and U comes after T.
then ‘CAT’ will be coded as ‘DBU’.