Correct Response: D. Most researchers of sheltered English immersion (SEI) acknowledge that a student's first language provides an important foundation for language and content learning in the second language. While English is the language of instruction in content-area classes that follow an SEI model, SEI teachers may use students' first language if needed to clarify communication. Research also strongly suggests that valuing students' first language builds confidence and motivation within students. A is incorrect as the statement is not supported by research. On the contrary, research shows that a strong foundation in the first language benefits students in learning additional languages. B is incorrect because English is the primary language of instruction in an SEI model. Conversely, C is incorrect because SEI does not prohibit use of students' first language in the classroom.