The reaction that occurs in soap making is known as saponification. Soap is formed by the combination of long chain monocarboxylic acids with sodium or potassium salts.

Option 1: Long chain monocarboxylic acids are the correct choice for soap making. These acids, such as stearic acid or oleic acid, have a long chain of carbon atoms with a carboxyl group at one end.

Option 2: Glycerol is a type of alcohol commonly used in soap making, but it is not the main component that reacts to form soap. Glycerol is often added to soap recipes to provide moisture and improve the texture of the soap.

Option 3: Long chain dicarboxylic acids have two carboxyl groups in their structure, making them unsuitable for soap making. Only monocarboxylic acids are used in the saponification process.

Option 4: Long chain tricarboxylic acids also have three carboxyl groups, which makes them unsuitable for soap making. Monocarboxylic acids are the preferred choice.

In summary, soap making involves the reaction between sodium or potassium salts of long chain monocarboxylic acids to form soap, making option 1