please help with this physics problem! please!?

Question

You are conducting an experiment inside a train car that may move horizontally along rail tracks. A load is hung from the ceiling on a string. The load is not swinging, and the string is observed to make a constant angle of 45 degrees with the horizontal. No other forces are acting on the load. which of the following statements are correct?

A.The train is an inertial frame of reference.
B.The train is not an inertial frame of reference.
C.The train may be at rest.
D.The train may be moving at a constant speed in a straight line.
E.The train may be moving at a constant speed in a circle.
F.The train must be speeding up.
G.The train must be slowing down.
H.The train must be accelerating.

Answer 1

B, C(instantaneously), E(if the track is curved), H are true.
All the others are false.

But why? I'll swat a couple of them for you. In an inertial frame, Newton's laws hold, so F=ma. However, in the train's reference frame, the load had unbalanced forces from gravity and string tension but is not accelerated relative to the train. F=ma does not hold, so the frame is not inertial. This decides A, B, and H.

Three in one blow! Not quite The Brave Little Tailor, but I'll take it...