$8.$ A $1$ kg block attached to a spring executes simple harmonic motion with a period of $0\mathrm{.}8$ s $.$ If the maximum kinetic energy of the block is $6$ J $,$ what is the amplitude of the motion?

a$)0\mathrm{.}22$ m

b$)0\mathrm{.}44$ m

c$)0\mathrm{.}66$ m

d$)0\mathrm{.}88$ m