The time period of a sample pendulum is to be determined with the help of a stop clock having a least count of $\large\frac{1}{3}$ seconds. If the estimated time period is about 2 second time for how many oscillations must be recorded so that the periodic time is determined with an error less than $0.67%$

Question

$\begin{array}{1 1}(A)\;6 \\(B)\;12 \\(C)\;18 \\(D)\;25 \end{array}$