Answer:
Strong base
Step-by-step explanation:
Lye is a base (metal hydroxide) which is obtained by leaching of ash.
Lye is generally used for sodium hydroxide and sometimes for potassium hydroxide also.
Lye is used in making of soap from oil or grease.
Lye is dissolved in water, and then it is used to treat oil which gives soap.
This process is generally referred as hot process.