[单选题]
A 2.0-kg mass is hung from a spring of spring mz7s w* b *ifwn5ii*h)con.brcd;k 3kkh+7xir*+ ky ba3-juc v(kstant 18 N/m, displaced slightly from its equilibrium p+kxjhkc+c avkr .( y7-iku33b; k brd*osition, and released. What is the frequency of its vibration?
A. $0.48 \; Hz$
B. $0.95 \; Hz$
C. $1.5 \; Hz$
D. none of the above