Timeboxing means setting a fixed, predefined amount of time for an activity or discussion, then stopping (or consciously extending via a decision) when that time expires. In the context of a kickoff meeting, timeboxing helps ensure the meeting stays controlled, covers required topics, and respects attendees' time. CompTIA Project+ explicitly includes timeboxing as part of meeting management techniques (along with agendas, roles, action items, and minutes).
Option D matches this definition precisely: "allowing a conversation to continue for a predefined period of time." Option A ("until a decision is made") is the opposite of timeboxing; it can lead to overrun and agenda failure. Option B suggests open-ended extension, again opposite of timeboxing's discipline. Option C describes a flexible timeline to cover everything, which usually increases meeting risk (scope creep within the meeting) rather than ensuring outcomes.
Practically, timeboxing in a kickoff might look like: 10 minutes for goals/success criteria, 10 for roles/RACI,
10 for scope boundaries, 5 for risks/assumptions, and 5 for next steps-creating focus, accountability, and a predictable meeting flow.