大全767，关于未划线处的主谓一致，请指教
767 The increased popularity and availability of televisions has led to the decline of regional dialects, language variations which originate from diverse ethnic and cultural heritages and perpetuated by geographic isolation.
(A) which originate from diverse ethnic and cultural heritages and perpetuated
(B) that originated from diverse ethnic and cultural heritages and perpetuated
(C) originated from diverse ethnic and cultural heritages and perpetuated
(D) originating from diverse ethnic and cultural heritages and perpetuated（D）
(E) originating from diverse ethnic and cultural heritages and perpetuating
这题正确答案选D我没疑问，但我不清楚的是，为什么句子主句的谓语动词要用单数形式，主语“The increased popularity and availability of televisions” 不是表达了两个概念“popularity”和“availability”吗，虽然公用了一个“the”、一个“increased”和一个“of television”，但不能否认“popularity”和“availability”是两个不同的概念呀？实际是说“the increased popularity of televistion and the increased availability of television”导致了......，所以我觉得应该用复数的谓语动词have led to。
请NN们指教，先谢了！ | 
