Two Events Occur Simultaneously on the X Axis of Reference

Multiple Choice

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 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