What is a 'mark'?

• A. The disc's design mark
• B. The defender guarding the thrower who counts the stall
• C. The boundary line mark
• D. A timekeeper's clock

Answer: (B)

In Ultimate, a mark is the defender who is guarding the thrower and counting the stall. This defender stays close to the thrower’s space and pressures them to release the disc before the stall count reaches ten. The mark’s job is to limit the thrower’s options and speed up decision-making, not to be a boundary line or a clock or any equipment mark.

So the correct choice identifies the mark as the defender guarding the thrower who counts the stall. The other descriptions refer to things unrelated to the on-field role of the mark, such as the disc’s design mark, boundary line markings, or a timekeeper’s clock.