Final answer:
The primary message conveyed in Montesquieu's Persian Letters was a critique of European society.
Step-by-step explanation:
The primary message conveyed in Montesquieu's Persian Letters was b) Critique of European society. Montesquieu used the fictional letters of two Persian travelers to provide a satirical critique of various aspects of European society, including the abuses of power by the French monarchy, the corruption of the Catholic Church, and the inequalities within European society. Through his criticism, Montesquieu aimed to highlight the need for political and social reform in Europe.