okay, can someone explain this to me because even one of the tuts thought it was a little silly.

On my physics assignment there was the following question:

You are conducting an experiment inside a train car that may move along level 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?

Check all that apply:

The train is an inertial frame of reference.

The train is not an inertial frame of reference.

The train may be instantaneously at rest.

The train may be moving at a constant speed in a straight line.

The train may be moving at a constant speed in a circle.

The train must be speeding up.

The train must be slowing down.

The train must be accelerating.

Now, I understand that it is not an inertial reference frame, i.e Newton’s laws do not apply. I know that the train could be travelling in a circular motion for this to occur and therefore the train is accelerating.
Why is instantaneously at rest one of the correct answers? Someone suggested to me, the train could just slam on the brakes and the object could swing out but that seems a little… random or non-methodical?
I’m not sure. But seriously, it’s the only thing that threw me on my whole assignment, I lost like, 2% for getting it wrong and ended up with a total on my assignment of 104% - I wanted full marks that piece of shit!