B. I think that John is looking glum to me.
An iamb is a syllabic foot made of 2 syllables with a unstressed syllable followed by a stressed syllable. Iambic pentameter is a line of poetry that has five (penta) iambs. This equals out to ten syllables per line. The only option that has ten syllables is B. Option A has 7 syllables, Option C has 11 syllables, Option D has 9 syllables.