To analyze the statements given in the question, we need to understand the historical context and relationships between the individuals and events mentioned.

1. Assertion (A): Burke criticised the French Revolution.
   • Edmund Burke was a prominent critic of the French Revolution. He expressed his criticisms through his famous work, "Reflections on the Revolution in France" (1790), where he argued that the drastic changes brought by the revolution would lead to chaos and tyranny.
   • Thus, the assertion that Burke criticised the French Revolution is indeed correct.
2. Reason (R): Thomas Paine's book, 'Rights of Man' was written in response to Rousseau.
   • Thomas Paine's "Rights of Man" was actually a rebuttal to Edmund Burke's criticisms of the French Revolution, not to Rousseau.
   • Paine's work defended the principles of the revolution, advocating for individual rights and egalitarianism, opposing Burke's conservative views.
   • Therefore, the reason given in the statement is incorrect.

Based on the explanation above, we can conclude that:

1. The Assertion (A) is correct because Burke did criticise the French Revolution, consistent with historical literature.
2. The Reason (R) is incorrect because Thomas Paine's "Rights of Man" was a response to Burke, not Rousseau.

Therefore, the correct answer is: (A) is correct but (R) is not correct.