Let he purchased an item @ Rs.100
Marked price = Rs. 130
We know that
Marked price - Discount = Selling price
ATQ
130 - 130*x % = 104
130 - 13x/10 = 104
x= 20
another way
Discount = MP - SP = 130-104 = 26
now w.r.t to marked price (26/130) ×100 =20
therefore option D