Which russian tsar supported intellectuals, poets, and playwrights and exchanged letters with enlightenment philosophers?

The correct answer is: "Peter the Great".

Peter the Great became tsar of Russia in 1682 and remained in power until his death in 1725. He enlarged the territorial possessions of the empire and, more importantly, he supported the cultural revolution based on the Enlightment and the replacement of medieval social and political systems with more modern ones based on scientific knowledge and reason.

i think its provide for the common defense

do you have a list of sources to choose from?