magnetism

A uniform magnetic field of intensity 1T is applied in a circular region of radius 0.1 m , directed into the plane of paper . A charged particle of mass 5 x 10 -5 kg and charge q = 5 x 10 -4 C enters the field with vel. 1/root 3 m/s makin an angle of phi with a radial line of circular region in such a way that it passes thru center of applied field . The angle phi is:
(A) 60 degrees
(B) 30 degrees
(C) 45 degrees
(D) 90 degrees