[单选题]
An electron is traveling at 0.85c. What is its massf:.x s31j1lrlng4xjm r vr./p? (The rest mass .mpviz*2w -u3d d r7cdis $9.11 \times 10^{-31} \; kg$.)
A. $1.4 \times 10^{-29} \; kg$
B. $7.2 \times 10^{-30} \; kg$
C. $1.7 \times 10^{-30} \; kg$
D. $2.4 \times 10^{-30} \; kg$