________the challenge of advertising this event, over one million people in at least 65 countries are expected to join in the next Buy Nothing Day.A. AlthoughB. ThoughC. DespiteD. In spite

本题考查介词短语的用法，核心在于区分连词与介词的用法差异。关键点在于：

1. Although/Though 是连词，需引导让步状语从句；
2. Despite/In spite of 是介词，需直接修饰名词或代词；
3. In spite 必须与 of 搭配使用，单独使用为错误形式。

选项分析

• A. Although 和 B. Though：作为连词，需后接从句（如 "Although advertising is challenging..."），但题目中空格后直接接名词短语，故排除。
• C. Despite：介词，可直接修饰名词短语 "the challenge of advertising this event"，符合语法要求。
• D. In spite：需与 of 搭配为 "In spite of"，单独使用错误。

结论

正确答案为 C. Despite，其后直接接名词短语构成完整介词结构。