Select the correct comparative form of the sentence ‘A string of pearls was not so bright as her teeth’-

Select the correct comparative form of the sentence ‘A string of pearls was not so bright as her teeth’-
(ক) Her teeth was more brighter than a string of pearls
(খ) Her teeth were brighter than a string of pearls
(গ) A string of pearls was brighter than her teeth
(ঘ) A string of pearls were very bright than her teeth