【正确答案】 C

【答案解析】解析：词汇题。本题考查用法易混的词语用法。A．happened vi．发生。常用句型：appen to+n．：发生到……上；happen on／upon sb．巧遇；happen to do(be)碰巧在做(在)；B．participated vi．参与。常用句型：participate in参与；participate with sb．in与……分享、分担；participate of含有，带有；C．involved vt．使……卷入，连累，包缠，使……专心于。常用句型：be involved in卷人，陷入；be involved in+n．或doing专心于；D．included vt．包括，包住；依据词义辨析可知C对。