A $70 - \mathrm { kg }$ Researcher Absorbs $4.5 \times 10 ^ { 8 }$

A $70 - \mathrm { kg }$ researcher absorbs $4.5 \times 10 ^ { 8 }$ neutrons in a work day, each of energy $1.2 \mathrm { MeV }$ . The relative biological effectiveness (RBE) for these neutrons is 10. What is the equivalent dosage of the radiation exposure for this researcher, in millirem?

A) $3.7 \mathrm { mrem }$
B) $1.2 \mathrm { mrem }$
C) $0.77 \mathrm { mrem }$
D) $0.39 \mathrm { mrem }$
E) $12 \mathrm { mrem }$