Thousands of dissidents have been ......or imprisoned in recent weeks.

Interrogated means to question someone formally and rigorously, especially about suspected crimes or political activities. In the context of dissidents (people who oppose government policies), 'interrogated' is the correct term. 'Inquired' is too mild, 'investigated' is broader, and 'probed' is less formal. The sentence describes political repression, where interrogation is commonly used.