Option A Dialogue means a conversation between two individuals as part of a book, movie, act or play.
Option B is an incorrect option because the meaning of Prologue is that the introduction or a preface of something.
Option C is an incorrect option because the word Epilogue is employed to explain the conclusion of something.
Option D may be an incorrect option because the word catalogue is a word wont to describe a guide or brochure to elucidate something.
Hence the right answer to the question which has the alternative intending to the word Monologue is option A. Dialogue which is an expression of speech through which two individuals can communicate a bit of knowledge with one another.