Essential Biochemistry - Vitamins (Section 6 - No. 43)
Thiamine (vitamin B1) consists of
a thiazole ring attached to a pyrimidine ring by methylene bridge
a benzene ring attached to a pyrimidine ring by methylene bridge
a thiazole ring attached to a benzene ring by methylene bridge
a pyrimidine ring attached to a thiazole ring by a hydrogen bridge
Explanation
Thiamine consists of a pyrimidine ring attached to a thiazole ring by a methylene bridge.