Which sequence of letters when placed in the blanks one after the other will complete the given letter series ?
-a--bba-ab-b

Options

A. babab
B. bbaaa
C. abbbb
D. aabbb

Explanation

To solve the problem of completing the letter series -a--bba-ab-b, we will analyze the given sequence and fill in the blanks step by step.

### Step 1: Identify the given sequence
The sequence provided is:
- _ a _ _ b b a _ a b _ b

### Step 2: Count the blanks
Let's count the blanks in the sequence:
- There are 6 blanks in total: 1st, 2nd, 3rd, 4th, 6th, and 7th.

### Step 3: Analyze the existing letters
The existing letters in the sequence are:
- 1st position: a
- 4th position: b
- 5th position: b
- 6th position: a
- 7th position: a
- 8th position: b
- 9th position: b

### Step 4: Look for patterns
Now, let's look for a pattern in the sequence:
- The letters 'a' and 'b' appear to alternate in some manner.

### Step 5: Test the options
We will test each option to see which one fits into the blanks:

1. **Option 1: b a b a b**
- Filling the blanks gives us: b a b a b b a b a b
- This does not fit as it disrupts the sequence.

2. **Option 2: b b a a a**
- Filling the blanks gives us: b a b b b b a a b
- This does not fit as it disrupts the sequence.

3. **Option 3: a b b b b**
- Filling the blanks gives us: a a b b b b a b
- This does not fit as it disrupts the sequence.

4. **Option 4: a a b b b**
- Filling the blanks gives us: a a a b b a b b
- This does not fit as it disrupts the sequence.

### Step 6: Find the correct sequence
After testing the options, we can see that:
- The correct sequence that fits the pattern is: **b a b a b**.

### Final Answer
The sequence of letters that will complete the given letter series is **b a b a b**.