"When I do count the clock that tells the truth" Why is the verse an example of iambic pentameter?

A) It has 10 stressed syllables of equal importance.
B) It has 5 metrical feet that each contain an unstressed syllable immediately followed by a stressed one.
C) It has 4 metrical feet that each contain a stressed syllable immediately followed by an unstressed one.
D) It has 10 unstressed words that sound as if they would be spoken by nobility.