[单选题]
A mass undergoes SHM with amplitude of 4 tb: ;io)qagh3 g i01*ckd;quzcm. The energy is 8.0 J at this time6)k g:rta5d qz. The mass is cut in half, and the system is again setga q6z5:rk d)t in motion with amplitude 4.0 cm. What is the energy of the system now?
A. $2.0 \; J$
B. $4.0 \; J$
C. $8.0 \; J$
D. $16 \; J$
