Two events that are simultaneous in one frame of reference will be:

A) simultaneous in all frames of reference
B) simultaneous in another frame that is moving in the opposite direction
C) simultaneous in another frame of reference that is moving in the same direction
D) simultaneous in the same frame of reference
E) simultaneous in another non-inertial frame of reference

I'm thinking "D" ..?

Yes, D, although it is a rather strange choice. All they are saying is "It is what it is".

To determine the correct answer, let's break down the options:

A) simultaneous in all frames of reference: This option implies that the events will be simultaneous in every possible frame of reference. However, this is not necessarily true. Simultaneity is relative and can depend on the observer's frame of reference, so it is not accurate to say that the events will be simultaneous in all frames of reference.

B) simultaneous in another frame that is moving in the opposite direction: This option suggests that the events will be simultaneous in a frame of reference moving in the opposite direction. However, the direction of motion does not necessarily affect simultaneity, so this option is not guaranteed to be correct.

C) simultaneous in another frame of reference that is moving in the same direction: This option suggests that the events will be simultaneous in a frame of reference moving in the same direction. Again, the direction of motion is not a determining factor for simultaneity, so this option is not necessarily correct.

D) simultaneous in the same frame of reference: This option suggests that the events will be simultaneous in the same frame of reference. Since the question states that the events are simultaneous in one frame of reference, it is logical that they would also be simultaneous in the same frame of reference. Therefore, this option (D) is correct.

E) simultaneous in another non-inertial frame of reference: This option pertains to frames of reference that are accelerating or experiencing non-inertial motion. However, the question does not mention any non-inertial frames of reference, so this option is not relevant to the question.

Based on the analysis above, the correct answer is D) simultaneous in the same frame of reference.