The correct answer is D) “Code switching”
Code switching is the process by which someone changes his/her language, dialect or register based on the context or setting. In this case for example, the student is adapting her register when speaking to the professor as the social context is different. When talking to her friend she uses an informal register and when speaking to the teacher she uses an informal register.
The abstract and concrete language options are not related to the change of language or register so they do not apply to the example. As regards polarization, it occurs when two or more groups are divided for having contrasting ideas.
