What option is available for walk-up ticket sales based on upper gallery capacity?

The correct answer addresses the procedure related to managing upper gallery capacity for walk-up ticket sales. Allowing overselling of capacity for walk-up tickets enables the venue to maximize attendance and revenue, particularly in scenarios where it can accommodate more guests than the stated limit, often based on experience with crowd management and safety.

This option is viable because it recognizes the potential flexibility in seating or space, where historical attendance patterns may suggest that not all ticket holders arrive simultaneously, or it could allow for additional guests in a standing area. It's a strategic choice to enhance the visitor experience while still adhering to safety guidelines.

The other options do not accurately address the capacity management of walk-up tickets in the same effective manner. Online sales only would restrict in-person attendance, limiting access; limiting ticket sales would prevent optimization of space; and offering free entry for students, while beneficial, doesn't speak directly to the specific issue of managing upper gallery capacity for ticket sales.