The answer is: D. A line of iambic pentameter contains five feet, with the unstressed syllable following the stressed syllable.
Iambic pentametric is a traditional kind of metric line in English poetry and verse. It involves a line of five feet or syllables - one unstressed syllable followed by a stressed one.
The rest of the alternatives are incorrect because they refer to three, four and six feet, and some of them state that the unstressed syllable comes after the stressed syllable.
