[单选题]
The average distance from the Earth to the yf ch6; ckcf uokj)5-:Sun is defined as h (7xux;tlt: uone "astronomical unit" (AU). An asteroid orbits the u;7tltux :xh( Sun in one-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. $5.2 \; AU$