Correct Option: A

Let the original price of the book be Rs. x.
∴ Number of books bought for Rs.200 = 200/x
and reduced price of the book=Rs.(x - 5)
∴ Number of books bought for Rs.200 = 200/(x - 5)
Now, according to the condition,
200/(x - 5) - 200/x = 2
⇒ (200x - 200x + 1000)/(x - 5)x = 2
⇒ (200x - 200x + 1000)/x(x - 5) = 2
⇒ 1000/x(x - 5) = 2
⇒ 1000/x(x - 5) = 1
⇒ 1000/x(x - 5) = 2
⇒ 500/x(x - 5) = 1
⇒ 500 = x(x-5)
⇒ x² -5x - 50 = 0
⇒ x²- 25 + 20x - 500 = 0
⇒ x(x - 25) + 20(x - 25) = 0
⇒ (x - 25)(x + 20) = 0
⇒ x - 25 = 0 or x + 20 = 0
⇒ x = 25 0r -20
⇒ x = 25 (since,x cannot be negatives)
So, the original price of the bok is Rs.25.