[单选题]
A 4.0-kg object is ati,rdy q+ rpk06tached to a spring of spring constaf/e ffnzq9nkh5)f;c , nt 10 N/m. The object is d)qfek, 5 f n9cf/h;fznisplaced by 5.1 cm from the equilibrium position and let go. What is the frequency of vibration?
A. $0.25 \; Hz$
B. $0.50 \; Hz$
C. $1.0 \; Hz$
D. $2.0 \; Hz$