答案：C

考查虚拟语气。根据If Lu Xun were a contemporary writer,，可知是考查含有if条件状语从句的虚拟语气，且是和现在事实相反，主句I can’t guarantee that he ________ laughed at by readers,要用助动词加动词原形，排除A,B；且根据as most young people don’t appreciate his writing style可知会被读者笑话，can’t表否定，再加上wouldn’t，双重否定表示肯定含义，所以选C。