[单选题]
A 4.0-kg object is attached c *bxiics.3u 6m ol+e3,7omdpn6x 1wkvdvs 00to a spring of spring constant 10 N/m. The object is displaced by0 skxvwd0 1vn6 5.1 cm from the equilibrium position and let go. What is the period of vibration?
A. $2.0 \; s$
B. $4.0 \; s$
C. $8.0 \; s$
D. $16 \; s$
