Question

choose the two sentences in this part of the text that prove nancy decided to listen to the flea.
the mean girls laughed at her, but secretly they were impressed.
suddenly nancy knew exactly what her flea friend had meant: nancy had tried to be nice to everyone except herself, but now she was determined to have fun.
nancy began to sing a camping song. many other girls joined in, though the \friend ship\ girls just kept grumbling among themselves. with her head held high, nancy helped counselor maria lead everyone to the mountaintop.
at the summit, counselor maria asked the campers to have a seat and said, \i have something to tell you. i put fleas in all the mattresses at the beginning of the week.\

Explanation:

The key is to find sentences showing Nancy's decision - based on the flea's message - to change her behavior. "Suddenly Nancy knew exactly what her flea friend had meant: Nancy had tried to be nice to everyone except herself, but now she was determined to have fun." shows she understood the flea. "Nancy began to sing a camping song." shows she acted on the understanding by starting to have fun.

Answer:

Suddenly Nancy knew exactly what her flea friend had meant: Nancy had tried to be nice to everyone except herself, but now she was determined to have fun.
Nancy began to sing a camping song.