Explanation:

To solve the problem, let's break down the information:

- The average of 5 numbers is 309. Therefore, the sum of the 5 numbers is \(5 \times 309 = 1545\).

- The average of the first two numbers is 431. Thus, their sum is \(2 \times 431 = 862\).

- The average of the last two numbers is 231.5, which means their sum is \(2 \times 231.5 = 463\).

- Now, using these sums:

- Total sum of all five numbers: 1545

- Sum of the first two numbers: 862

- Sum of the last two numbers: 463

- The sum of the first two numbers and the last two numbers cover four of the five numbers.

- The number at the center of the row can be found by subtracting these sums:

- Center number = Total sum - (Sum of the first two + Sum of the last two)

- Center number = \(1545 - (862 + 463) = 1545 - 1325 = 220\)

- Correct Answer is Option:4, 220