Since free$-$range eggs are eggs produced from hens that may be permitted outdoors and therefore reduce the amount of suffering involved in producing eggs, which ethical standard would most clearly support buying free$-$range over traditionally farmed eggs that keep the birds packed in cages and never let them out to roam freely.

a$.$ Kant $($rights$)$

b$.$ Mill $($utility$)$

c$.$ Rawls $($justice$)$

d$.$ Dussel $($material principle$)$