Consider the following sets. U = {all triangles} E = {x|x ∈ U and x is equilateral} I = {x|x ∈ U and x is isosceles} S = {x|x ∈ U and x is scalene} A = {x|x ∈ U and x is acute} O = {x|x ∈ U and x is obtuse} R = {x|x ∈ U and x is right} Which is a subset of I? E S A R