[单选题]
A simple pendulum executing si
x oemb9clm0b( lr93s6qbe. /z t cn:mow;wo/ 2mple h
:pys9aqw5dv y;;pih 0v5 uh/tn;s4waarmonic motion is released from one end and reaches equilibrium positi
v;t: vs50h 4p ;d5s;wn p/ayihq 9yuawon in $2\,s$. Just after the equilibrium position, the length of the pendulum is reduced to one-fourth of its initial value because of wrapping around a nail.
What is the period of the simple pendulum?