Which of the following enhances the lathering property of soap?

We need to identify which substance enhances the lathering property of soap.

Lathering refers to the formation of foam when soap is mixed with water. To improve lathering, substances called builders or lather boosters are added to soap.

Considering the given options:

- Sodium stearate: This is itself a soap (sodium salt of stearic acid). It does not specifically enhance lathering.

- Sodium carbonate: This is a water softener (washing soda). It helps soap work in hard water but does not directly enhance lathering.

- Sodium rosinate: This is the sodium salt of rosin (abietic acid), obtained from pine trees. It is specifically added to soap to increase lather formation. Rosin soap produces rich, stable foam.

- Trisodium phosphate: This is a cleaning agent and water softener but does not enhance lathering.

Sodium rosinate is added to soaps as a lather-enhancing agent. It improves the foaming ability of the soap. Hence, the correct answer is Option C.