Who or what functions as a symbol in this passage

“i didn't know that cheshire cats always grinned; in fact, i didn't know that cats could grin.” “they all can,” said the duchess; “and most of 'em do.” “i don't know of any that do,” alice said very politely, feeling quite to have got into a conversation. “you don't know much,” said the duchess; “and that's a fact.” what is the effect of the short sentences on the dialogue? they make the dialogue smooth and serene. they make the dialogue lively and humorous. they make the dialogue formal and elegant. they make the dialogue into a song.

Could someone me with this question?

Aprimary source: a- may be biased b- is never biased c- cannot possibly have bias d- none of the above