In how much time (in years), will a sum of money become thrice of itself at the rate of 25% per annum simple interest?

For an amount to become three times itself, the interest gained on that amount must be twice its value.

Let the value of the amount be P, and the number of years it takes for the interest gained on that amount is 2P can be calculated as,

$$SI=\dfrac{P\times\ T\times\ R}{100}$$

$$2P=\dfrac{P\times\ T\times\ 25}{100}$$

$$T\ =\ 8$$ years.

Therefore, the time it takes for the amount to become three times its value is 8 years.

Hence, the correct answer is option B.