Teaching a pronunciation class to a mixed group of learners can ________ a teacher with many challenging problems．
A.provideB.produceC.presentD.offer在线课程C
解析：
考查词汇辨析：present sb．with sth．：造成某人……：把不同程度的学员混合在一起教授语音给教师带来很多挑战性的问题。