Final answer:
Both the assertion that Regimes of 1815 did not tolerate criticism and the reasoning that conservative regimes were autocratic are true, with the autocratic nature providing an explanation for the lack of tolerance for criticism.
Step-by-step explanation:
The question is about whether the assertion that Regimes of 1815 did not tolerate criticism is true and if the reasoning that this was due to the conservative regimes being autocratic is correct. Looking at the historical context, after the defeat of Napoleon, the Congress of Vienna in 1815 sought to restore the old order with a conservative ideology that indeed did not tolerate much criticism, as leaders tried to maintain their power and suppress liberal movements.
Therefore, it would be correct to say that both statement A and statement R are true; moreover, the autocratic nature of conservative regimes can be seen as a reason why they did not tolerate criticism. Thus, the option that would be accurate in this context is 'a. Both A and R are true, and R is the correct explanation of A.'