At What Distance from the Center of the Earth Would $\mathrm{R}$

Multiple Choice

At what distance from the center of the Earth would one's weight be one third of that recorded on the Earth's surface? Let the Earth's radius be $\mathrm{R}$ .

A) $1.7 \mathrm{R}$
B) $0.4 \mathrm{R}$
C) $1.4 \mathrm{R}$
D) $0.5 \mathrm{R}$
E) 3R
F) $\mathrm{R}$