Which two numbers should be interchanged to make the given equation correct?
$$35 + 3 \div 3 - 5 + 1 = 40$$

$$35+\frac{3}{3}-5+1=40$$

A. 40 and 35
$$40+\frac{3}{3}-5+1=35$$

$$40+1-5+1=35$$

$$41-5+1=35$$

$$36+1=35$$

$$37=35$$

B. 1 and 5

$$35+\frac{3}{3}-5+1=40$$

$$35+\frac{3}{3}-1+5=40$$

$$35+1-1+5=40$$

$$35+0+5=40$$

$$40=40$$

C. 1 and 35

$$1+\frac{3}{3}-5+35=40$$

$$\frac{4}{3}-5+35=40$$

$$1.33-5+35=40$$

$$-3.66+35=40$$

$$31.34=40$$

D. 35 and 5
$$35+\frac{3}{3}-5+1=40$$

$$5+\frac{3}{3}-35+1=40$$

$$\frac{8}{3}-35+1=40$$

$$2.66-35+1=40$$

$$-32.33+1=40$$

$$-31.33=40$$

Hence option B is the correct answer