Final answer:
Imipramine is the drug most closely related to Carbamazepine, as both are tricyclic antidepressants with similar structural characteristics.
Step-by-step explanation:
Carbamazepine is closely related to Imipramine, making option 3 the correct answer. Both Imipramine and Carbamazepine are structurally related, as they both contain a tricyclic ring system, which is significant for their biological activity. This classification of compounds is referred to as tricyclic antidepressants. Imipramine is one of the drugs most widely used for the treatment of major depression and is chemically similar to other tricyclic antidepressants. The tricyclic structure is characterized by a three-ring core and, in the case of Imipramine, includes a tertiary amine group.
In contrast, the other drugs listed such as Sodium Valproate, Quinidine, and Metoprolol have different chemical structures and pharmacological effects. Therefore, they are not closely related to Carbamazepine. Sodium Valproate is often used in the treatment of epilepsy and bipolar disorder, Quinidine is an antiarrhythmic agent used to treat heart rhythm disorders, and Metoprolol is a beta-blocker used to treat hypertension and angina.