Not supported. The study involving high school students, described in P2, never suggested that speakers are always aware of the reasons they code-switch. So a study showing that speakers are sometimes unaware of their code-switching wouldn’t cast doubt on the study in P2.

Not supported. We have no reason to think the results of the study described in P2 are unexpected. The only mention of expectations is in connection with code-switching due to rhetorical factors in P3.

The study of a family of Puerto Rican Americans is discussed in P3. There’s no evidence that research conducted before this was ever thought by “most” researchers to explain code-switching in “all except the most unusual or nonstandard context.” Although P3 shows that situational factors aren’t the only reason people code-switch, there’s no indication that over half of researchers ever thought that situational factors explained all code-switching with only a few exceptions.

Although P3 shows that people can be unaware of their code-switching, and P2 shows that sometimes, people have conflicting views about what topic or language mix fits with various situational factors, there’s no evidence that people who code-switch are “usually unaware” of which situational factors might influence their language choice.

Supported. The family was asked about why they occasionally used Spanish at home, as heard in recorded conversations. They said it was used to express certain attitudes more emphatically. That’s an example of code-switching for rhetorical effect. The family didn’t point to any other reason for speaking Spanish at home. In addition, the author introduces the discussion of the family by noting that code-switching sometimes occurs “only sparingly to achieve certain rhetorical effects.” The study of the family is mentioned to support this claim. The author doesn’t suggest the potential for any other reason the family would code-switch at home.