I don't have any----- in learning English grammer,but I ofte

应该是make spelling mistakes吧.
选C
这里是说在学语法上没遇到什么困难,一般用短语have diffuiculty in doing sth.而且这里前面是any,所以用复数.
trouble一般用于麻烦烦恼.problem一般指问题.
其实这几个区别很小.不过选项A和C都是difficulty,显然是要你从两个里面选.要选复数,所以选C.