Which of the Following Is TRUE About Language Variation

Which of the following is TRUE about language variation?

A) Languages vary grammatically and orthographically, but not lexically
B) Every speaker of a dialect uses the same set of linguistic features
C) Languages vary phonologically and lexically, but not orthographically
D) Speakers can only have one variety of a language in their idiolect
E) Linguistic changes that occur within different groups of speakers often lead to language variation