120, 135, 126, 141, 132, 143, 138

Options

A. 135
B. 132
C. 126
D. 143

Explanation

To find the odd one out from the series: 120, 135, 126, 141, 132, 143, 138, we will analyze the pattern of differences between the numbers.

### Step-by-Step Solution:

1. **Identify the Series**: The series is 120, 135, 126, 141, 132, 143, 138.

2. **Calculate the Differences**:
- Between 120 and 135:
\[ 135 - 120 = 15 \]
- Between 135 and 126:
\[ 126 - 135 = -9 \]
- Between 126 and 141:
\[ 141 - 126 = 15 \]
- Between 141 and 132:
\[ 132 - 141 = -9 \]
- Between 132 and 143:
\[ 143 - 132 = 11 \]
- Between 143 and 138:
\[ 138 - 143 = -5 \]

3. **List the Differences**:
- The differences we calculated are: 15, -9, 15, -9, 11, -5.

4. **Identify the Pattern**:
- The pattern appears to alternate between adding 15 and subtracting 9:
- +15, -9, +15, -9
- However, after the last two differences, we see a deviation:
- Instead of following the pattern, we have +11 and then -5.

5. **Determine the Expected Value**:
- Following the established pattern, after 132 (which is followed by 143), we should add 15:
\[ 132 + 15 = 147 \]
- Thus, the number that should be in place of 143 is 147.

6. **Identify the Odd One Out**:
- Since 143 does not fit the established pattern (it should have been 147), we conclude that 143 is the odd one out.

### Final Answer:
The odd one out in the series is **143**.