[单选题]
An electron is traveling a rcjb+t 26gj;ii z6f.q5c qo/qt 0.85c :h 0ay;/kq hy j frh8gzaui54n04g:ki5(boba. What 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. $2.4 \times 10^{-30} \; kg$