您在为一家旅游公司制作视频广告，目的是增加其网站上的预订量。 您应在此广告中使用以下哪种号召性用语 (CTA)？

立即预订" (Book Now) is the most effective CTA because it directly aligns with the campaign's objective: increasing bookings on the website. This CTA clearly tells users the desired action and is highly relevant to a travel company's service. "立即致电" (Call Now) might be suitable for some businesses but bypasses the website booking goal. "欢迎光顾" (Welcome) is too generic and doesn't prompt any specific action. "了解详情" (Learn More) is a softer CTA that encourages exploration rather than immediate conversion, making it less direct for a booking-focused campaign.