[单选题]
If you walk 5.0 m horizontally forward at a constant velocity w 6d1l/bju5fch)m5)3tmb defcarryin tkxs ihxxsg,5bb ru+f9vcc4 ;8s)+7 ig a 10-N object, thev;,ks4 5ti sfirh+u+bc 9 s8)xcx7xbg amount of work you do is
A. more than 50 J.
B. equal to 50 J.
C. less than 50 J, but more than 0 J.
D. zero.
