[单选题]
A 4.0-kg object is attached to a spring of spring cf v1vf)ew+8o(q c3ar aonstant w wf-+ ogezrj7j a9to6 c4vqy1o:7jr9 10 N/m. The object is d-gq+jt1rjo 9z ya4fcvoj9o7erw :6 7w isplaced 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. $16 \; s$
