"that" as a determiner or complementizer

• On projects in the built environment, people consider safety and functionality nonnegotiable. But the aesthetics of a new project―how it is designed―is too often considered irrelevant ― The question of how its design affects human beings is rarely asked. People think that design makes something highfalutin, called architecture, and that architecture differs from building, just as surely as the Washington National Cathedral differs from the local community church.

Q. I was curious about the grammatical role of the second "that". Some teachers think it functions as a complementizer linked with the main verb "think". Others think it functions as a determiner as in "that cousin of ours".

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