A pattern formed by two characters a and b is repeated more than once in the following string: × b × a × a × × a × a × bab What is ×× in the 7th and 8th positions from the left in the above string?

விடையைக் காட்டு & விளக்கம்

விடை: (D) bb

விளக்கம்

Known letters fit a repeating block of 5, 'abbab': positions 1-15 read abbab abbab abbab. Positions 7 and 8 are both 'b'.