Answer:
The words "frivolous ground" found in the first paragraph means foolish claims. For example, the " Older and wiser and better people had told him he was not to talk nonsensense", showing that what Nicholas is claiming is so ridiculous and foolish that he was not to continue what he was saying, because it was not of any value. Additionally, the text states that " Nicholas was not to be of the party; he was in disgrace." Nicholas claiming that there was a frog in his bread-and-milk was so absurd that he was in disgrace and he was not to attend the party. Therfore the words "frivolous grounds" used in paragraph one means foolish claims or absurd thinking.
Step-by-step explanation: