Alice Bungee-Jumps from a Bridge Above a Deep Gorge $D$ Be Alice's Departure from Bob's Location on the Bridge, and Watches

Multiple Choice

Alice bungee-jumps from a bridge above a deep gorge. Bob watches from the bridge. Let event $D$ be Alice's departure from Bob's location on the bridge, and event $R$ be her return to Bob's location on the bridge. Carol observes these events from a a train passing over the bridge, and uses synchronized clocks on the train to measure the time between Alice's departure and return.
-(b) Which person's watch or clocks register(s) the space time interval between those events?

A) Alice
B) Bob
C) Carol
D) Alice and Bob
E) Bob and Carol
F) Alice and Carol
G) All three observers