The correct answer is C. anapestic tetrameter
An anapest is a metrical foot that contains of two unstressed syllables followed by a stressed syllable. “Understand” and “contradict” are cases of anapest, because both of them have three syllables where the accent is on the final one. An anapestic tetrameter comprehends four metrical feet of three syllables in an anapestic form, including twelve syllables overall, such as the line above.