The reason for choosing option (4) "praising herself" as the correct meaning of the idiom "Sanya kept blowing her own trumpet throughout the party" is as follows:

The idiom "blowing her own trumpet" is a figurative expression that means bragging or self-promotion. It suggests that someone is talking about their achievements, abilities, or qualities in a boastful or self-aggrandizing manner. In the context of the sentence, it indicates that Sanya was continuously praising herself during the party, which aligns with the meaning of the idiom.

The other options do not accurately capture the meaning of the idiom:

- Option (1) "chatting continuously" does not convey the sense of self-promotion or boasting inherent in the idiom.
- Option (2) "irritating everyone" is related to the effect of the behavior described by the idiom but does not directly represent the self-praising aspect.
- Option (3) "singing loudly" is unrelated to the idiom's meaning.