Answer:
B. Iambic trimeter (The foot has an unstressed syllable followed by a stressed syllable. This pattern repeats three times in each line.)
Explanation:
Alfred Edward Housman's poem "<em>When I was one and twenty</em>" was a part of the collection of poems "A Shropshire Lad". This particular poem may have been written about his personal affection and one sided love of a man named Moses Jackson.
<em>"When I was one-and-twenty</em>
<em>I heard a wise man say"</em>
The lines of the poem has a difference in number of syllables. The first line has seven syllables and the second has six syllables. This keeps on alternating in the following lines till the end. So, all of the even-numbered lines contains three stressed and unstressed syllables, thus making it an iambic trimeter. This means that the foot has an unstressed syllable followed by a stressed syllable, where this pattern is repeated three times in each line.