D. tetrameter and pentameter
Within lines of poetry, there are elements called “feet.” A foot is composed of one stressed and one unstressed syllable; thus, one foot equals two syllables. The two most common types of metrical lines in English poetry are tetrameter and pentameter. Tetrameter has four feet, and pentameter has five feet. As such, a line that has four feet will have eight syllables, and a line that has five feet will have ten syllables.
As an example, the following is a line in tetrameter:
I wish | to know | the one | who sings.
Here is an example of a line in pentameter:
You thought | you would | be here | until | the end.