Non-Native Spanish Speakers Often Have Difficulty Rolling the "Rr" Consonant

Non-native Spanish speakers often have difficulty rolling the "rr" consonant.Why does this most likely occur?

A) This phoneme may not exist in the speaker's language,so he or she has difficulty with this novel pronunciation.
B) This morpheme may not exist in the speaker's language,which might make pronunciation difficult.
C) The syntactical structure has no meaning to the non-native speaker who needs to develop an association with this consonant to his or her native language.
D) Those who learn to speak Spanish learn a different grammar and,therefore,have difficulty differentiating between a rolled "r" and the "r" sound of their native language.