Who is the author of the classic novel "The Adventures of Tom Sawyer"?

Introduction / Context:
"The Adventures of Tom Sawyer" is a classic American novel often read by children and adults alike. It portrays the mischievous adventures of a boy growing up along the Mississippi River. Because of its popularity and influence, exams often ask about its author. Identifying Mark Twain as the writer of this novel demonstrates knowledge of major works in English language literature, especially those that shaped the genre of coming of age stories.

Given Data / Assumptions:
• The title given is "The Adventures of Tom Sawyer". • It is known as a classic novel about a boy's adventures. • Four authors are suggested, from different periods and countries. • Only one of them actually wrote this book. • The question focuses on matching book and author, not on plot analysis.

Concept / Approach:
Mark Twain, whose real name was Samuel Langhorne Clemens, is a key figure in American literature. He wrote "The Adventures of Tom Sawyer" and its companion novel "Adventures of Huckleberry Finn". The other options belong to different literary traditions: John Ruskin was a Victorian critic, William Shakespeare was a playwright, and Leo Tolstoy was a Russian novelist. The correct approach is to recall that Tom Sawyer and Huckleberry Finn are iconic Mark Twain characters representing American childhood.

Step-by-Step Solution:
1. Recall that Tom Sawyer is a boy who lives in a small town along the Mississippi River and engages in playful mischief. 2. Remember that Mark Twain created this character and used his stories to comment on society, friendship, and morality. 3. Examine option d, Mark Twain, and recognise this as the correct author. 4. Consider option a, John Ruskin, who wrote essays on art and society, not children's adventure novels. 5. Consider option b, William Shakespeare, who wrote plays and sonnets, with no novels among his works. 6. Consider option c, Leo Tolstoy, a Russian writer known for long novels like "War and Peace", unrelated to Tom Sawyer. 7. Conclude that Mark Twain is the correct and only suitable answer.

Verification / Alternative check:
Every edition of "The Adventures of Tom Sawyer" lists Mark Twain as the author on the cover. Literature courses on American writing treat this novel as one of his signature works. In contrast, Shakespearean studies focus on drama and poetry, Tolstoy is discussed in Russian literature, and John Ruskin appears in critical essays on art and architecture. This separation of fields and genres confirms that option d is correct.

Why Other Options Are Wrong:
• John Ruskin did not write novels about fictional children in the American South; his work focuses on art criticism and social thought. • William Shakespeare was a dramatist and poet from the Elizabethan era, not a novelist. • Leo Tolstoy wrote Russian novels about aristocratic and peasant life, not about Tom Sawyer.

Common Pitfalls:
Sometimes candidates choose William Shakespeare simply because he is the most famous English writer listed, even though he never wrote novels. Others may confuse different classic authors when they see several big names together. To avoid this, it is helpful to remember simple associations such as Mark Twain with Tom Sawyer and Huckleberry Finn, Shakespeare with plays like "Hamlet" and "Othello", and Tolstoy with "War and Peace".

Final Answer:
The classic novel "The Adventures of Tom Sawyer" was written by Mark Twain.