Right choice is (b) 44.74∠-303.4⁰A
The explanation is: Taking the line voltage VRY = V∠0⁰ as a reference VRY = 400∠0⁰V, VYB = 400∠-120⁰V and VBR = 400∠-240⁰V. Impedance per phase = (4+j8) Ω = 8.94∠63.4⁰Ω. Phase current IB = (400∠240^o)/(8.94∠63.4^o) = 44.74∠-303.4⁰A.