A is 25 percent more than B. B is how much percent less than A?

Correct option is B

According to question,
Let the price of B = x
A = B + 25% of B = x + 0.25x = 1.25x

​$$\text{Percentage less} = \frac{A - B}{A} \times 100$$

$$\text{Substitute the values of } A \text{ and } B:$$

$$\text{Percentage less} = \frac{1.25x - x}{1.25x} \times 100 = \frac{0.25x}{1.25x} \times 100$$

$$\text{Simplifying:} \quad \text{Percentage less} = \frac{0.25}{1.25} \times 100 = 0.2 \times 100 = 20\%$$​​​