[单选题]
An electron is traveling at 0.85c. What ist,d8l c. o8e(xbwd 5pae6 g+eb its mass? (The rest mass ixq )b(d .*9cjgz s1 n3w lck;amakk,g9s $9.11 \times 10^{-31} \; kg$.)
A. $1.4 \times 10^{-29} \; kg$
B. $7.2 \times 10^{-30} \; kg$
C. $1.7 \times 10^{-30} \; kg$
D. $2.4 \times 10^{-30} \; kg$
