What was the outcome of the tennis match?

The choice indicating that the tennis match "was called off" accurately conveys that the match did not take place as planned. This term specifically means that the event has been cancelled, often due to unforeseen circumstances such as weather conditions, player unavailability, or other factors that make it impossible to conduct the match.

In contrast, "was postponed," implies that the match will be held at a later time but still indicates an intention to play. "Was delayed" suggests that the match would commence later than scheduled but doesn't imply that it won't occur at all. "Was rescheduled" also suggests that the match is not cancelled but rather moved to a different date or time. These options do not capture the definitive conclusion that the match will not happen in any form, which is why "was called off" is the most suitable choice for the given context.