A mass M is connected to a spring with spring constant k$,$ and it is oscillating with a

period T$.$ If $45$ kg is added to the original mass, the period is found to quadruple. The

original mass, M$,$ is:

A$)9$ kg

B$)5$ kg

C$)3$ kg

D$)6$ kg

E$)1\mathrm{.}5$ kg