Which statement correctly defines the structure of the iambic pentameter meter? a. a line of iambic pentameter contains four feet, with the unstressed syllable following the stressed syllable. b. a line of iambic pentameter contains three feet, with the stressed syllable following the unstressed syllable. c. a line of iambic pentameter contains six feet, with the stressed syllable following the unstressed syllable. d. a line of iambic pentameter contains five feet, with the unstressed syllable following the stressed syllable.