A 2-M Long 6 Kg Ladder Pivoted at the Top

Multiple Choice

A 2-m long 6 kg ladder pivoted at the top hangs down from a platform at the circus. A 42 kg trapeze artist climbs to a point where her centre of mass is at the centre of the ladder and swings at the system's natural frequency. The angular frequency (in s-1) of the system of ladder and woman is:

A) 1.01.
B) 3.07.
C) 4.03.
D) 8.05.
E) 16.2.