您在制作视频广告，目的是帮一家旅游公司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 call to action (CTA) because it directly aligns with the campaign's objective: increasing website bookings for a travel company. This CTA encourages immediate action that leads to a conversion. "了解详情" (Learn More) is too passive and might not drive direct bookings. "欢迎光顾" (Visit Us) is vague and doesn't specify the desired action. "立即致电" (Call Now) might be suitable for some businesses, but for increasing website bookings, it diverts users from the primary conversion path on the website.