[单选题]
An object of mass m isvf. .c4wt oe1;r4g(sj:k dnv v frgx : ev9i6zu vp2ay;b8nnub1.oo7rpa/ 45fhanging by a string from the ceiling of an elevator. The elevi4u;o.z b5y/ r26punf7g9 81 e avpfb rx:aovnator is moving upward, but slowing down. What is the tension in the string?
A. less than mg
B. exactly mg
C. greater than mg
D. zero
