Apply Gauss's theorem to calculate the electric field of a thin infinitely long straight line of charge, with a uniform charge density (λ).

a) (E = λ/2πϵ₀r)
b) (E = λ/4πϵ₀r)
c) (E = 2λ/πϵ₀r)
d) (E = λ/πϵ₀r)