Choose the set of letters that sequentially completes the following letter series.
ab_aa_aaa_a_ab_a
Show answer & explanation
Correct answer: D
Explanation
The given series consists of 16 letters and follows a repeating pattern of 4 letters: abaa.
Dividing the series into groups of 4 letters:
abaa / abaa / abaa / abaa
The letters that complete the blanks are abbaa.