Answer : Option B

Explanation :

The C.P of 4 article is rupees 5 and selling price of 5 article is rupees 4.

Note: article ratio should be the same in both cases.

i.e.,     Article    price

C.P =      4       5

S.P =      5       4

As the article is same in both the cases, we should make the article equal.

To make article value equal, we need to multiply C.P with 5 and S.P with 4. The change made in Article should also be performed at a price to calculate the % profit or loss.

i.e.,         Article         price

C.P =       4* 5 = 20       5* 5 = 25

S.P =        5 * 4= 20       4* 4 = 16

The difference between the price of C.P and S.P is 25-16 = 9.

Now, apply % formula:

Profit or Loss % = ((difference between C.P and S.P)/ C.P) * 100

Note: if S.P > C.P = profit
If C.P > S.P = loss

Here C.P = 25, and S.P = 16

So, Loss % = (9/25) * 100 = 36%

Hence, the person incurs a loss of 36%.