You Want a Mass That,when Hung on the End of a Spring,oscillates

Multiple Choice

You want a mass that,when hung on the end of a spring,oscillates with a period of 1 s.If the spring has a spring constant of 10 N/m,the mass should be

A) 10 kg
B) kg
C) 4 $\pi$ ²(10) kg
D) 10/(4 $\pi$ ²) kg
E) None of these is correct.