The correct option is
A deabc
In the given series, the pattern being followed is
a b c d e–/ b c d–– e a––/ c– d e a–– b / d––e–a––b–c– which follows a cyclic order.
Since the letters missing are more than five, so in the answer only the last five letters would come.
Therefore, the last five missing alphabets are deabc.
Hence, option A is correct.