Definition of trigger events is the best way to enable the timely execution of an incident response plan because it helps to specify the conditions or criteria that initiate the incident response process. Trigger events are predefined scenarios or indicators that signal the occurrence or potential occurrence of a security incident, such as a ransomware attack, a data breach, a denial-of-service attack, or an unauthorized access attempt. Definition of trigger events helps to ensure that the incident response team is alerted and activated as soon as possible, as well as to determine the appropriate level and scope of response based on the severity and impact of the incident. Therefore, definition of trigger events is the correct answer.