Generally speaking, the more luxuries people have, the higher their value or social status—or 12 they believe.
答案：(B) so
or so they believe 是固定說法，意為「至少他們是這麼認為的」，帶保留語氣，暗示作者未必同意；still、yet、even 都無法構成這個說法。
答對率 30%。
or 與 so 你都認得，合起來卻看不懂——這是固定說法，拆開推測沒有用。or so they believe 放在一句陳述之後，等於中文的「至少他們是這麼想的啦」，作者用它來與前面那句話保持距離，暗示自己不見得同意。
前半句 the more luxuries people have, the higher their value or social status（東西買得越多，身價與社會地位就越高）本身就是一個很可議的說法；下一句提到「跟不上鄰居」會被視為社經地位低落，通篇帶著批判語氣。作者需要一個保留的標記，or so they believe 正好。
or so I thought（我本來是這麼以為的）、or at least that's the idea（至少理論上是這樣）、supposedly（據稱）。
or so they believe（至少他們是這麼認為的）、or so I thought（我本來是這麼以為的）、keep up with the Joneses（與人攀比）、keep up appearances（維持體面）。
"Keeping up with the Joneses" is a catchphrase in many parts of the English-speaking world. Just like "keeping up appearances," it refers to the 11 to one's neighbors as a standard for social status or the accumulation of material goods. Generally speaking, the more luxuries people have, the higher their value or social status—or 12 they believe. To fail to "keep up with the Joneses" is thus perceived as revealing socio-economic inferiority or, as the Chinese would put it, a great loss of face.
The 13 was popularized when a comic strip of the same name was created by cartoonist Arthur R. "Pop" Momand. The strip was first published in 1916 in the New York World, and ran in American newspapers for 28 years before it was eventually 14 into books, films, and musical comedies. The "Joneses" of the title were rich neighbors of the strip's main characters and, interestingly, they were merely 15 but never actually seen in person in the comic strip.