What theme does rahul develop by describing his work in ashok's fish shop in free from school?

I think the theme would be "exploration". Throughout the story, Rahul had learned so many things that he never thought that he would be learning in school.  There were so many first times and learnings that he had learned from Ashkok's fish shop. He was able to breed fishes and learned the feeling of accomplishing something on your own.

(C) Regret

Explanation:

“Regret” is one example of an abstract word. Abstract nouns are words that represent the names of objects but objects that are objects that cannot be captured by the five senses such as the name of the situation, the name of the job, the name of the attribute, the name of the size, and so forth. For example beliefs, benefits, welfare, air, knowledge, goodness, ideas.