C) 1 m
Explanations:
The time period of a simple pendulum is
\(T=2\pi\sqrt\frac{L}{g}\)
Where L is the length of the pendulum.
\(L=\frac{gT^2}{4\pi^2}\)
The time period of the simple pendulum which ticks seconds is 2s.
\(\therefore T=2s\)
Substituting in (i), we get
\(L=\frac{{(9.8ms^-2)}{(2s)^2}}{{4\times}{(3.14)^2}}=1m\)