Explanation:

To solve this problem, you need to replace the signs in the equation based on the instructions:

- 39 + 3 ÷ 4 - 1 × 3 becomes:

- Replace `+` with `÷`, `÷` with `×`, `×` with `-`, and `-` with `+`.

- The expression becomes: 39 ÷ 3 × 4 + 1 - 3

- Solve the expression step-by-step:

1. 39 ÷ 3 = 13

2. 13 × 4 = 52

3. 52 + 1 = 53

4. 53 - 3 = 50

- Compute the options:

- Option 1: 46

- Option 2: 50

- Option 3: 53

- Option 4: 51

- Result: The final value is 50.

- Select the option: Option 2, 50

Hence, the correct answer is: Option 2: 50