Which role does the assistant referee play when an offense occurs in their view?

The role of the assistant referee is to support the main referee in their decision-making process. When an offense occurs within the view of the assistant referee, they provide critical assistance by signaling any infractions they observe. This can include actions such as indicating offside positions, or other fouls that are not directly seen by the referee, thus ensuring that all rule violations are noticed and addressed appropriately.

This cooperative approach enhances the overall officiating of the match, as the assistant referee's observations allow the referee to make more informed decisions. The assistant referee's signals serve to communicate information effectively, while the final authority to call a foul still rests with the referee.

The other options do not align with the established responsibilities of the assistant referee. They do not make final decisions, nor are they limited to notifying the referee only for major fouls. Additionally, while they may play a role in player substitutions, this is not their primary responsibility when it comes to on-field offenses. Thus, the option indicating their role in signaling offenses they observe is the accurate description of their duties.