The correct answer is A. Iambic tetrameter
Explanation:
In poetry, the meter refers to the way verses are composed including the number of syllables in each verse and whether these syllables are stressed or not, which provides rhythm to poems. In English poetry one of the most common units for meter is called "iamb" which is composed of an unstressed or short syllable followed by a stressed or long syllable, additionally to this, verses can have different number of "iambs" including two iambs or iambic diameter; three iambs or iambic trimeter; four iambs or iambic tetrameter; five iambs or iambic pentameter, etc.
In the case of the verse presented "This is my letter to the world", this verse is composed of eight syllables "This/is/my/le/tter/to/the/world" and each pair of syllables is composed by an unstressed syllable and one stressed syllable marked by the symbol (') "This 'is my 'letter 'to the 'world", this means this verse is composed of iambs and has four iambs which make this verse an example of iambic tetrameter.
