The formation of a solid, also known as a is an indication of a chemical change.

The formation of a solid, also known as a precipitation reaction, is an indication of a chemical change.

Precipitation reaction talks about when a solid substance formed in the water, or the reaction upon mixing two aqueous (water-like or containing water) solutions.

it’s previous models   because when i picked that son of a gun’s answer it was wrong look for previous models because they might make it a different letter