[单选题]
Two objects collide and stick toge57o6abx 2 m y)epkvwkuq g)r20therbughf,p;* 6 073tiomhob sl6c. Kinetic energy
A. is definitely conserved.
B. is definitely not conserved.
C. is conserved only if the collision is elastic.
D. is conserved only if the environment is frictionless.
