Primary amines can be distinguished from secondary and tertiary amines by reacting with
a) Chloroform and alcoholic KOH
b) Methyl iodide
c) Chloroform alone
d) Zinc dust

hint: It is the isocyanide test. From the name we will guess the isocyanide is the product because in between the reactant nobody is isocyanide. How secondary and tertiary amine reacts.

Step-by-step solution
The reaction of Chloroform with primary amine and alcoholic KOH is called isocyanide test because the product is an iso-cyanide.
Amines are nitrogenous organic compounds that contain one or more carbon-nitrogen double bonds. Amines are classified into primary, secondary, and tertiary amines, depending on the number of carbon atoms attached to the nitrogen atom. Primary amines have one carbon atom attached to the nitrogen atom, secondary amines have two carbon atoms attached to the nitrogen atom, and tertiary amines have three carbon atoms attached to the nitrogen atom.
Amines are very important in organic chemistry. They are used as intermediates in the synthesis of many important organic compounds, such as drugs and pesticides. The identification of amines is very important in the laboratory. One of the most common tests for amines is the isocyanide test.
The isocyanide test is a simple test that can be used to identify amines. The test involves the reaction of an amine with an isocyanide reagent. The isocyanide reagent is a compound that contains the group -N=C=O. When the isocyanide reagent is added to an amine, it reacts with the nitrogen atom to form a cyanide ion. The cyanide ion is a very strong poison and is very toxic.
The isocyanide test is often used to identify primary amines. The test can be used to distinguish between primary and secondary amines. Secondary amines do not react with the isocyanide reagent, but primary amines do. The test can also be used to identify tertiary amines. Tertiary amines do not react with the isocyanide reagent, but primary and secondary amines do.
The isocyanide test is a very simple test that can be used to identify amines. The test is quick and easy to perform, and it does not require any special equipment. The test is also very sensitive and can detect very small amounts of amines.

From the above discussion we get that our answer is a .

 Note: The reaction of Chloroform with aniline and alcoholic KOH is called isocyanide test because the product is an iso-cyanide. Only, primary aliphatic and aromatic amines provide it. It helps for distinguishing primary amines from secondary and tertiary amines.