97, 77, 59, 43, 26, 17

Options

A. 77
B. 59
C. 43
D. 26

Explanation

To solve the series completion problem, we need to identify the pattern in the given series: 97, 77, 59, 43, 26, 17.

### Step-by-Step Solution:

1. **Identify the Series**: We have the numbers: 97, 77, 59, 43, 26, 17.

2. **Calculate the Differences**:
- 97 to 77: \( 97 - 77 = 20 \)
- 77 to 59: \( 77 - 59 = 18 \)
- 59 to 43: \( 59 - 43 = 16 \)
- 43 to 26: \( 43 - 26 = 17 \)
- 26 to 17: \( 26 - 17 = 9 \)

The differences are: 20, 18, 16, 17, and 9.

3. **Look for a Pattern**:
- The differences do not form a consistent pattern, but we can observe that the numbers are decreasing.
- Let's analyze the pattern further by checking if there is a consistent subtraction pattern.

4. **Check for a Squaring Pattern**:
- Let's check if squaring numbers and subtracting gives us the series:
- \( 10^2 - 3 = 97 \)
- \( 9^2 - 4 = 77 \)
- \( 8^2 - 5 = 59 \)
- \( 7^2 - 6 = 43 \)
- \( 6^2 - 8 = 28 \) (this should be the next number)
- \( 5^2 - 8 = 17 \)

5. **Identify the Incorrect Number**:
- From our calculations, we see that instead of 26, we should have 28 in the series.
- Therefore, the incorrect number in the series is 26.

6. **Conclusion**:
- The wrong number in the series is **26**.

### Final Answer:
The incorrect number in the series is **option D: 26**.