A firm produces output according to a fixed proportion production function f(x₁,x₂)=Min{3x₁,x₂}.Assume that the cost of factor 1is $1 and the cost of factor 2 is $2.What does the firm's cost function c(y) look like?

I.8y/3

II.7y/3

III.5y

IV.7y

(multiple choice)