Iron has the lowest oxidation state in

It is given that among the 4 different iron compounds which have the lowest oxidation state for Fe.

let the oxidation number of Fe be x

FeSO₄= x+(+6)+(-2(4))

=x-2

x=+2

K₄[Fe(CN)₆] = 1(4)+x+(-1(6))

=4+x-6

x=+2

Fe(CO)₅ = x+(0(5))

x=0

FeO = x+(1(-2))

x=+2

Among the four compounds, Fe(CO)₅ has the lowest oxidation state for Fe. Hence, the correct option is C.