Answer:
A. An unstressed syllable followed by a stressed syllable
Step-by-step explanation:
In poetry, an iamb is a metrical foot (a group of syllables) that has one UNSTRESSED syllable followed by a STRESSED syllable. For example, the word remark is an example of an iamb because re is an unstressed syllable and mark is a stressed syllable.
Lines of poetry can contain different types of iambs depending on the number of iambs that there are per line. These types are dimeter (two iambs per line), trimester (three iambs), tetrameter (four iambs), pentameter (five iambs) or hexameter (six iambs).