Which language acquisition theory would you say most applies to this student, and the instruction you'd apply to her?
The language acquisition theory that most applies to the student is the Brain-Based Theory because the student is in the “silent stage” where they listen more than produce, and teachers should be patient and appreciate this silence as real language develops slowly, beginning with speaking (Krashen, 1982).
I will continue my teaching using my ELL techniques because I cannot force the student to speak while his/her brain is in the middle of this process. As Krashen stated, we need to be patient: Rome was not built in one day.