[单选题]
A 2.0-kg mass is attached to the enih 1+hk7q3hnpuxq -.cjmv:e0d4rs 1u*g;ffr7wcuih- of a horizontal spring of spring constant 50 N/m and set into simple harmonic motion with an amplitude of ui 1;7c*4fg-rfrhus w 0.10 m. What is the total mechanical energy of this system?
A. $0.020 \; J$
B. $25 \; J$
C. $0.25 \; J$
D. $1.0 \; J$