Five events occurred in a sequence: E1, E2, E3, E4, and E5. E1 happened before E3 but after E2. E4 happened after E3 but before E5. What is the correct order of the events?
Answer: A. E2, E1, E3, E4, E5
E2 must occur first, followed by E1, then E3, then E4, and finally E5.