Answer: b. iamb (an unstressed syllable followed by a stressed syllable)
Explanation:
The foot pattern used is that of an Iamb.
An Iamb is one of the most popular metrical feet in Poetry and was used intensively by Shakespeare.
A word is considered an Iamb when it starts with unstressed syllable followed by a stressed syllable. This means that while the first syllable is short, the following syllable is accented and long. For example, among or instead. It can be two words like she-will.
In a line it follows the same concept, an unstressed syllable, followed by a stressed syllable.
In the above that would be,
Coming with vivid faces
From counter or desk among grey.
