[单选题]
The average distance f2fxr2(kk h dhlm:*r,: soh7xtrom the Eaw;2les +t)qsxju;rk3 1uh2kcrth to the Sun is defined as one "astronomical unit" (AU). An asteroid orbits the Sun in one lxq2 13sk;kjtwhesc; +)ruu 2-third of a year. What is the asteroid's average distance from the Sun?
A. $0.19 \; AU$
B. $0.48 \; AU$
C. $2.1 \; AU$
D. $5.2 \; AU$