34, 40, 57, 86, 128, 185, 2,55

Options

A. 40
B. 128
C. 57
D. 185

Explanation

To find the odd one out in the series: 34, 40, 57, 86, 128, 185, 255, we will analyze the differences between consecutive terms.

### Step-by-Step Solution:

1. **Identify the Series**: The series given is:
\[ 34, 40, 57, 86, 128, 185, 255 \]

2. **Calculate Differences**: We will calculate the differences between consecutive terms:
- \(40 - 34 = 6\)
- \(57 - 40 = 17\)
- \(86 - 57 = 29\)
- \(128 - 86 = 42\)
- \(185 - 128 = 57\)
- \(255 - 185 = 70\)

So, the differences are:
\[ 6, 17, 29, 42, 57, 70 \]

3. **Calculate Differences of Differences**: Next, we will find the differences of these differences:
- \(17 - 6 = 11\)
- \(29 - 17 = 12\)
- \(42 - 29 = 13\)
- \(57 - 42 = 15\)
- \(70 - 57 = 13\)

So, the second level differences are:
\[ 11, 12, 13, 15, 13 \]

4. **Identify the Pattern**: We observe that the second level differences do not follow a consistent pattern. The expected differences should increase by 1 each time:
- After 11, we expect 12 (which we have),
- After 12, we expect 13 (which we have),
- After 13, we expect 14 (but we have 15),
- After 15, we expect 16 (but we have 13).

5. **Correcting the Series**: If we assume the correct difference after 42 should be 14, then:
- The next term after 128 should be \(128 + 14 = 142\) instead of 185.

6. **Finding the Odd One Out**: The term 185 does not fit the expected pattern. Instead, we should have 142. Therefore, the odd one out in the series is:
\[ \text{185} \]

### Conclusion:
The odd one out in the series is **185**.