Two events occur simultaneously on the x axis of reference frame S, one at x = −a and the other at x = +a. According to an observer moving in the positive x direction:
A. the event at x = +a occurs first
B. the event at x = −a occurs first
C. either event might occur first, depending on the value of a and the observer’s speed
D. the events are simultaneous
E. none of the above
