Final answer:
Exceptionally successful L2 learners can have different outcomes compared to true monolingual native speakers, and it can vary and be unpredictable. The correct option is d). Variable and unpredictable.
Step-by-step explanation:
d). Variable and unpredictable. The question of whether exceptionally successful L2 (second language) learners can be indistinguishable from native speakers elicits contrasting opinions. Language proficiency involves various factors, including pronunciation, vocabulary, grammar, and cultural nuances. Some argue that exceptionally successful L2 learners can reach a level similar to true monolingual native speakers, while others believe there may be subtle differences, making them different from true monolingual native speakers. The variability arises from individual differences, learning environments, exposure, and the age at which the second language was acquired. Some L2 learners achieve a remarkable level of proficiency, appearing indistinguishable from native speakers, while others may retain subtle accents or exhibit minor differences in language use. Therefore, the outcome can be variable and unpredictable based on numerous factors.