Answer:
Option A,C
Explanation:
u= 4 ˆi : v =2(√3ˆi+ˆj)

According to the figure , magnetic field should be in ⊗ direction , or along -z direction
Further , tanθ=vyvx=22√3=1√3
∴ θ=300orπ6
= angle of v with x-axis
= angle rotated by the particle
=Wt =(BQM)t
∴ B=πM6Qt
=50πMQ units 9as t =10-3 second)