Correct Option (4)
The given series is `_ b _ a _ ba _ b _ abab _ aab`. To identify the correct sequence for the blanks, we must determine the underlying pattern of the series.
Upon analyzing the structure, the series follows a repeating block pattern of `(abb)(aab)`. This block is repeated three times consecutively:
- First block: `a b b`
- Second block: `a a b`
- Third block: `a b b`
- Fourth block: `a a b`
- Fifth block: `a b b`
- Sixth block: `a a b`
When this pattern `a b b a a b a b b a a b a b b a a b` is applied to the original series with blanks, the characters filling the blanks are:
- Blank 1: `a`
- Blank 2: `b`
- Blank 3: `a`
- Blank 4: `b`
- Blank 5: `a`
- Blank 6: `b`
Thus, the sequence `ababab` correctly completes the series, forming a consistent repeating pattern.
Incorrect Options:
Substituting the sequences from the other options into the blanks does not yield a consistent or discernible repeating pattern:
- Option 1 (bababa): Inserting `bababa` results in `b b a a b b a b b a a b a b a a b`. This sequence does not exhibit a uniform repeating block.
- Option 2 (baabba): Inserting `baabba` results in `b b b a a a a b b b a a b b a a b`. This sequence lacks a clear, consistent pattern.
- Option 3 (bbaabb): Inserting `bbaabb` results in `b b b a a a a b b b a a b b b a a b`. This arrangement also fails to establish a regular repeating pattern.