Hard
A letter series follows a hidden pattern: a _ ba _ bb _ ab _ aab _ a. Which option correctly fills the five blanks in order?
Explanation
Explanation
If we repeat the 4-letter block 'abba' continuously (abba abba abba abba), it reads: a-b-b-a-a-b-b-a-a-b-b-a-a-b-b-a, and this matches every given letter in the sequence exactly. Reading off the letters that fall in the five blank positions gives b, a, a, b, b - that is, 'baabb'.
PRO TIP
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