In the following question, out of the four alternatives, select the alternative which is the best substitute of the phrase.
Causing a burning sensation like that of hot liquid on the skin

Let's check the meanings of all the given words:
scalding: very hot; burning or injuring with very hot liquid or steam. This perfectly matches the definition.

piping: very hot (usually used to describe food or water, as in "piping hot").

igneous: relating to or involving volcanic or geothermal processes (rocks formed from solidified magma or lava).

sizzling: making a hissing sound, as of food frying or cooking.

Thus, scalding is the correct substitute.