Veronal and luminal are the derivatives of barbituric acid which are an important class of tranquilizers.

1). Let us now discuss about barbituric acid. Derivatives of barbituric acid, which is Verona, amytal, Nembutal, luminal and seconal constitute an important class of tranquilizers. These derivatives are called barbiturates. Barbiturates are hypnotic that is sleep producing agents.

2). Non-narcotic analgesics (non-addictive) are the non-addictive drugs reduce or abolish pain without causing impairment of consciousness, mental confusion, incoordination or paralysis or some other disturbances of nervous system.

3). Antiallergic drugs controls allergies by controlling histamines. (histamine is a potent vasodilator. It has various functions.)

4). Neurologically active drugs are antidepressant drugs which inhibit the enzymes which catalyse the degradation of noradrenaline.

Hence, option (i)Tranquilizer is the correct option. Options (ii), (iii) and (iv) are incorrect.