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In the word, A and C have one letter between them , in alphabetical order A and C have only letter B between them
C and E have one letter between them , in alphabetical order C and E have only letter D between them
A and E have three letter between them , in alphabetical order A and E have three letters B, C and D between them
Therefore, (A,C) ; (C,E) and (A,E) are three pairs which satisfy the given condition.
Option D is correct