Answer:
"Mark Twain" AND "Adventures of Huckleberry Finn" AND "childhood"
"Huckleberry Finn" AND "childhood"
"Mark Twain" AND "childhood"
"Adventures of Huckleberry Finn" AND "childhood"
All of the above keyword combinations would be effective in beginning a search for information on the theme of childhood in Mark Twain's book Adventures of Huckleberry Finn. By including the name of the author and the title of the book, you can narrow your search to specific sources that are relevant to your research topic. Adding the keyword "childhood" will further narrow your search to sources that specifically address this theme in the book.
Step-by-step explanation: