The figure shows a region of length 'l' with a uniform magnetic field of 0.3 T in it and a proton entering the region with velocity $$4 \times 10^5$$ m s$$^{-1}$$ making an angle 60$$°$$ with the field. If proton completes 10 revolution by the time it cross the region shown, 'l' is close to (mass of proton $$= 1.67 \times 10^{-27}$$ kg, charge of the proton $$= 1.6 \times 10^{-19}$$ C):

A

0.11 m

B

0.88 m

C

0.44 m

D

0.22 m