The Bottom End of a Ladder Rests on a Floor $\theta$

Multiple Choice

The bottom end of a ladder rests on a floor with friction. The ladder leans against a frictionless vertical wall, the length of the ladder making an angle $\theta$ with the wall. A boy is perched on the ladder at such a point that equilibrium of the system is barely maintained. The ladder will slip under any of the following independent changes except

A) if the boy's distance from the top is decreased.
B) if the boy's mass is decreased.
C) if µ is decreased.
D) If $\theta$ is increased.