What literary device is characterized by a character speaking their thoughts aloud?

The correct choice is soliloquy because it specifically refers to a character expressing their thoughts and feelings aloud, usually while alone on stage, allowing the audience to gain insight into their inner thoughts. This device is commonly used in drama, particularly in Shakespearean plays, to convey a character's motivations, desires, or conflicts without the influence or interruption of other characters.

In contrast, dialogue involves conversation between two or more characters, while a monologue is a lengthy speech by one character that may or may not be directed to others. An aside is a brief remark made by a character that is intended to be heard by the audience but not by other characters on stage. Each of these devices serves different purposes in storytelling and character development, but a soliloquy is distinct in its focus on a single character's introspective thoughts shared directly with the audience.