[单选题]
An electron is traveling.agjq gl2x : ao7k)hr9 at 0.85c. b5hl:7udm4d 8urne k . 28tabeWhat is its mass? (The rest mass is $9.11 \times 10^{-31} \; kg$.)
A. $1.4 \times 10^{-29} \; kg$
B. $7.2 \times 10^{-30} \; kg$
C. $1.7 \times 10^{-30} \; kg$
D. $2.4 \times 10^{-30} \; kg$