What type of estimation techniques are used when durations of activities are highly predictable?

The correct answer is deterministic duration estimation techniques, which are utilized when the durations of activities are highly predictable. Deterministic estimates rely on historical data, expert judgment, or established best practices, leading to confident and exact predictions about the time it will take to complete particular tasks. This predictability allows for a more straightforward planning process as project managers can set clear timelines with fewer uncertainties involved.

In contrast, probabilistic duration estimation techniques incorporate uncertainty and variability, making them more suitable for activities where outcomes are less predictable. Timebox estimation is generally used for tasks within a set timeframe without assessing the exact duration necessary, and while relative estimation techniques can offer a quick comparison between tasks based on their complexities, they do not provide the concrete durations required in highly predictable scenarios. Therefore, deterministic methods are the appropriate choice when the goal is to achieve reliable and accurate time frames for task completion.