225, 375, 312, 431, 261, 711

Options

A. 225
B. 312
C. 431
D. 261

Explanation

To solve the problem, we need to analyze the given series of numbers: 225, 375, 312, 431, 261, 711. We will check the divisibility of each number by 3.

### Step 1: Check the divisibility of each number by 3
To determine if a number is divisible by 3, we can sum its digits and check if the result is divisible by 3.

1. **225**:
- Sum of digits: 2 + 2 + 5 = 9 (divisible by 3)

2. **375**:
- Sum of digits: 3 + 7 + 5 = 15 (divisible by 3)

3. **312**:
- Sum of digits: 3 + 1 + 2 = 6 (divisible by 3)

4. **431**:
- Sum of digits: 4 + 3 + 1 = 8 (not divisible by 3)

5. **261**:
- Sum of digits: 2 + 6 + 1 = 9 (divisible by 3)

6. **711**:
- Sum of digits: 7 + 1 + 1 = 9 (divisible by 3)

### Step 2: Identify the exception
From our calculations, we see that all numbers except **431** are divisible by 3.

### Conclusion
The pattern in the series shows that all numbers are divisible by 3 except for 431. Therefore, the answer to the question is that 431 is the only number in the series that is not divisible by 3.

### Final Answer
All numbers are divisible by 3 except 431.

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