Why do you consider the sentence incomplete when the context of the sentence you quoted is quite clear.
FWIW, it was beaten over our heads in school that merely writing “Yes.” in response to a question is not a complete sentence, but that may have been a pedagogical rule rather than a grammatical rule, to force students to learn proper grammar.
A sentence will generally not make sense out of context[0] anyway.
Why do you consider the sentence incomplete when the context of the sentence you quoted is quite clear.
FWIW, it was beaten over our heads in school that merely writing “Yes.” in response to a question is not a complete sentence, but that may have been a pedagogical rule rather than a grammatical rule, to force students to learn proper grammar.
A sentence will generally not make sense out of context[0] anyway.
0: https://en.wikipedia.org/wiki/Sentence_(linguistics)#Major_a...