[单选题]
An electron is traveling at 0.85c. What is its mass? (The rest mass ..v7r w7asg4cvl4yn-t *p wo pirek n gm8+inj; it*ra3q+ tc17s $9.11 \times 10^{-31} \; kg$.)
A. $1.4 \times 10^{-29} \; kg$
B. $7.2 \times 10^{-30} \; kg$
C. $1.7 \times 10^{-30} \; kg$
D. $2.4 \times 10^{-30} \; kg$