What analogy represents a similar relationship as "run : marathon"?

The relationship in the phrase "run : marathon" is that running is an activity that culminates in the specific event of a marathon, which is a long-distance race primarily focused on running.

The choice that best mirrors this relationship is "swim : triathlon." In this analogy, swimming is one of the components of a triathlon, much like running is essential to a marathon. A triathlon comprises multiple events, including swimming, cycling, and running, where swimming is a critical and specialized part of the overall competition, just as running is central to participating in a marathon.

In contrast, other options do not capture the same relationship. For example, "hike : trek" may suggest similar outdoor activities but does not denote a specific event associated with hiking. "Ride : bicycle" indicates an action associated with a mode of transport but does not reference a specific competitive event where riding is a primary focus. Lastly, "jump : long jump" describes a specific type of jumping event, but it does not convey the broader event structure that is present in the relationship of swimming to triathlon. Thus, "swim : triathlon" maintains the essence of an activity leading to a recognized competitive event.