[单选题]
96.14: A 30-kg child who is running at 4.0 m/s jbym sx(w*dbaa-5lu97 umps onto a s o8*i a+plfc)ia9b5gx tationary 10 kg skateboard. The speed of the child and the skateboard is approxim9)b5o8ila* pgiax f+cately:
A. 3.0 m/s
B. 4.0 m/s
C. 5.0 m/s
D. 6.0 m/s
E. 7.0 m/s
