问题：
[单选题]Signaling nouns help create and maintain continuity in text, and thus such nouns are also refers to as ____.
Aabstract nouns
Btext-referring words
Cformal nouns
Dproper nouns
[单选题]Signaling nouns help create and maintain continuity in text, and thus such nouns are also refers to as ____.
Aabstract nouns
Btext-referring words
Cformal nouns
Dproper nouns
