Step 1: Identify the author of *Piers the Plowman*.
*Piers the Plowman* is a medieval English allegorical poem written by William Langland. It is considered one of the most important works of Middle English literature.
Step 2: Analyze the options.
- (A) Spenser: Incorrect. Edmund Spenser was a later poet, known for *The Faerie Queene*, not *Piers the Plowman*.
- (B) Milton: Incorrect. John Milton wrote *Paradise Lost*, not *Piers the Plowman*.
- (C) Langland: Correct. William Langland is the author of *Piers the Plowman*.
- (D) Congreve: Incorrect. William Congreve was a Restoration playwright, not the author of *Piers the Plowman*.
Step 3: Conclusion.
The correct answer is William Langland.