1 Poe really was the inventor of the detective story, which he called the "ratiocinative" tale. 2 Here believing the effect intended was "to perplex the reader and whet his desire for elucidation," he originated two devices useful to this day. 3 One might be called "the device of the baffled friend": He gave his brilliant detective a companion not good at solutions and had him tell the story. 4 Viewing the happenings through this narrator's eyes, the reader shares his growing puzzlement. 5 Poe used his second device at the tale's end: He had the detective DISCLOSE his surprising solution and then "elucidate" step by step the reasoning which led to it. 6 "The Purloined Letter" demonstrated Poe's use of these two devices in a detective story. What is the meaning of the prefix in the word disclose, as it is used in the paragraph?

a. down or away from
b. without or outer
c. similar to or alike
d. in addition to or with