A cylindrical air bearing is made by taking a fixed porous rod and fitting around it a slightly oversized sleeve. Air is forced out through the pores in the rod, causing the sleeve to ride on a thin air cushion. Which of the following is the most complete description of what can be said about the forces and moments that the rod imposes on the sleeve?

A. $F_x = 0$
B. $F_x = 0$ and $M_y = 0$
C. $F_x = 0$ and $M_z = 0$
D. $F_x = 0$, $M_y = 0$, and $M_z = 0$
E. $F_x = 0$ and $M_x = 0$