Correct Answer: (b) A meter whose foot is made of one unstressed syllable followed by stressed syllable.
Solution:In iamb is such a foot having two syllables : the first unstressed or 'weak' and the second stressed for example: The word 'belong', when we pronounce this word; the first syllable 'be' was softer comparatively when we say the second part 'long'. Hence, option (b) is correct.