[单选题]
A metal sphere of radius 10 cm carriesp4mzav+u o+m* a charge of /1z u( zjw,yl w;dl8aj+2.0 mC. What is the magnitude of the elect y 8wua1z, lzwj(;j/ldric field 5.0 cm from the sphere's surface?
A. $4.0 \times 10^{5} \; N/C$
B. $8.0 \times 10^{5} \; N/C$
C. $4.0 \times 10^{7} \; N/C$
D. $8.0 \times 10^{7} \; N/C$