The correct answer for the question is: The connection between an event or action and the resulting event or action in a story's plot.
A causal relationship as its name hints is the correlation between two events, in this case within a text. As for to say that one event produces a change in the other. For example, <em>Andrew was supposed to pick up Andrea to go to the airport but he lost his car keys so they missed their flight. </em>There is a casual relationship between the event of Andrew loosing his car keys and them losing their flight because one event caused the other.