Which of the following is NOT a factor that affects second language acquisition (L2)?

The choice of native language fluency as a factor that does not affect second language acquisition is valid because while native language proficiency can influence how a learner acquires a second language, it is not considered a direct determinant like motivation, age, or social conditions. Motivation plays a crucial role, as it directly impacts a learner's desire and dedication to learning the new language. Age is also a significant factor because younger learners often acquire new languages more easily due to cognitive and developmental advantages. Social conditions, including the environment in which a person is learning the language, can greatly influence language acquisition by providing necessary exposure and opportunities for communication. Thus, while native language fluency may shape the learning experience, it does not straightforwardly affect the inherent ability to acquire a second language in the same fundamental way that the other options do.