[单选题]
A 4.0-kg object is attached to a spring of sprp5bhs,5yg(i d7gk y +vevqg) *vk.:p)zf9 r yding constant a nd4;4 h5hex -r8dzdd10 N/m. The object is 48h;d -d renaxd4d hz5displaced by 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. $16 \; s$
