Who is the author of the book "Preparing for the Twenty-First Century"?

Introduction / Context:
This question refers to "Preparing for the Twenty-First Century", a non fiction book that discusses global economic, social, and political challenges as the world moves into a new era. It is often mentioned in the context of international relations, global studies, and strategic planning. Examinations include such titles to test students' awareness of influential works that analyse future trends. The goal here is to identify Paul Kennedy as the author.

Given Data / Assumptions:
• The book title is "Preparing for the Twenty-First Century". • It deals with global change and future challenges. • Four authors associated with international affairs and literature are listed. • Only one author actually wrote this book. • The question is about correct authorship, not thematic details.

Concept / Approach:
Paul Kennedy is a historian and scholar known for works on global power shifts, including "The Rise and Fall of the Great Powers". "Preparing for the Twenty-First Century" extends his analysis to emerging issues such as population, environment, and technology. V. S. Naipaul is primarily a novelist and travel writer, John Ruskin was a Victorian critic and essayist, and Henry Kissinger is a diplomat and author of different works on diplomacy. The correct approach is to connect the forward looking, analytical nature of the book with Paul Kennedy.

Step-by-Step Solution:
1. Observe that the title clearly signals a focus on the future and on preparing societies for upcoming challenges. 2. Recall that Paul Kennedy wrote extensively on the long term patterns of global power and later on issues facing the world in the new century. 3. Examine option c, Paul Kennedy, and link his name with this analytical, research based book. 4. Consider option a, V. S. Naipaul, best known for literary and travel works, not for this type of global forecasting study. 5. Consider option b, John Ruskin, a nineteenth century critic whose writings focus on art, society, and morality, not on modern twenty first century challenges. 6. Consider option d, Henry Kissinger, a diplomat and author known for books on diplomacy and foreign policy but not for this particular title. 7. Conclude that Paul Kennedy is the only author that fits the book mentioned.

Verification / Alternative check:
Verification can be done by recalling that bookshops and academic reading lists on global issues consistently list "Preparing for the Twenty-First Century" under Paul Kennedy's name. In contrast, V. S. Naipaul's works emphasise personal narratives about postcolonial societies, John Ruskin belongs to a much earlier era, and Henry Kissinger's notable books include "Diplomacy" and "World Order". This clear separation in style and period confirms that option c is correct.

Why Other Options Are Wrong:
• V. S. Naipaul is a Nobel laureate in literature but did not write this analytical book on twenty first century preparation. • John Ruskin wrote in the nineteenth century and could not have authored a book specifically about the twenty first century. • Henry Kissinger writes about diplomacy and international relations from a practitioner's perspective, but he is not the author of this title.

Common Pitfalls:
Candidates sometimes link any book about global affairs with Henry Kissinger because of his fame as a diplomat. Others may choose V. S. Naipaul based solely on name recognition, without noting the non fiction academic nature of the title. To avoid such errors, it is important to remember that Paul Kennedy is the historian associated with predictive and analytical works on global power and future challenges, including "Preparing for the Twenty-First Century".

Final Answer:
The book "Preparing for the Twenty-First Century" was written by historian Paul Kennedy.