What is the central idea of summer of mariposas chapter 18

The next day Papa and Jay Berry watch Grandpa's store. Grandpa and Grandma take Mama and Daisy into town and load them onto the train to Oklahoma City. They are gone for six weeks. During that time Jay Berry realizes how much he misses his mother and sister. He also realizes how much work his mother does around the house. He becomes melancholy as the summer turns into fall, dreaming about his pony. His father becomes melancholy as well, and spends many long evenings rocking on the porch smoking his pipe. In town, Grandpa becomes very grouchy, too. The mail comes once a week and Mama always writes a letter. She tells how Daisy's operation is a success, how Daisy's cast comes off, and how Daisy is learning to walk again. Finally the letter says they are coming home. Papa and...

Explanation:

a: it is sound because it cites an expert’s opinion.