Match List-I (Drug) with List-II (Class of Drug):
(a) Furacin              (i) Antibiotic
(b) Arsphenamine   (ii) Tranquilizers
(c) Dimetone          (iii) Antiseptic
(d) Valium              (iv) Synthetic antihistamines
Choose the most appropriate match:

First, we recall the basic definitions of the four classes of drugs mentioned in List-II:

$$\text{(i) Antibiotic:}$$ A chemical substance produced by microorganisms (or prepared synthetically) that can inhibit the growth of or destroy other microorganisms.

$$\text{(ii) Tranquilizer:}$$ A compound that acts on the central nervous system and reduces anxiety or tension, producing a calming effect.

$$\text{(iii) Antiseptic:}$$ A substance applied to living tissues to prevent the growth of disease-causing microorganisms.

$$\text{(iv) Synthetic antihistamine:}$$ A man-made drug that blocks the action of histamine, thereby reducing allergic symptoms.

Now we examine each drug in List-I one by one and connect it with the correct class.

We have Furacin, whose chemical name is nitrofurazone. It is routinely applied on wounds, burns and skin infections to stop microbial growth. The definition that matches this property is that of an antiseptic. So we write

$$\text{Furacin}\;(a)\;\longrightarrow\;\text{Antiseptic}\;(iii)$$

Next, we consider Arsphenamine. This drug, historically called Salvarsan, was the first effective treatment for syphilis and is obtained from microbial action or prepared synthetically to kill the causative bacterium. By our definition, such a compound is an antibiotic. Hence,

$$\text{Arsphenamine}\;(b)\;\longrightarrow\;\text{Antibiotic}\;(i)$$

Now, Dimetone remains. Dimetone is the trade name for diphenhydramine-like compounds that counteract histamine and alleviate allergic symptoms such as cold and sneezing. Compounds of this type are man-made and therefore fall under the class of synthetic antihistamines. Consequently,

$$\text{Dimetone}\;(c)\;\longrightarrow\;\text{Synthetic antihistamine}\;(iv)$$

Finally, Valium is the well-known trade name for diazepam, a benzodiazepine that soothes the central nervous system and is widely prescribed to relieve anxiety and induce calmness. Such drugs are categorized as tranquilizers. Thus,

$$\text{Valium}\;(d)\;\longrightarrow\;\text{Tranquilizer}\;(ii)$$

Collecting all four correct correspondences in the same order as the lists, we get

$$ \begin{aligned} (a)&\to(iii),\\ (b)&\to(i),\\ (c)&\to(iv),\\ (d)&\to(ii). \end{aligned} $$

We now compare this complete mapping with the given options. We observe that Option D lists exactly the pairings $$\bigl[(a)-(iii),\,(b)-(i),\,(c)-(iv),\,(d)-(ii)\bigr],$$ which matches our analysis.

Hence, the correct answer is Option D.