If d₁ is the depth of cutting, d₂ is the height of the bank from bed level r₂ : 1 and r₁ : 1 are the slopes in filling and cutting respectively, the horizontal distance n between the bed and bank, is_____.

A)
x = r₁ d₁
B)
x = r₂ d₂
C)
x = d₁ / r₁
D)
x = d₂ / r₂

Correct Answer :   x = r₂ d₂