* The interface must collect structured input: start date, end date, PTO days. * A waterfall dialog is designed for step-by-step data gathering. Each step asks one question and collects one piece of information, minimizing complexity. * Skill dialog is for invoking another bot. * Adaptive dialog handles interruptions and dynamic flow (more complex). * Component dialog organizes dialogs but does not simplify sequential data collection. The answer: B Reference: Waterfall dialogs in Bot Framework