The correct answer is option 1: a rock. Evaporites are rocks that are formed as a result of the evaporation of water. When water evaporates, it leaves behind dissolved minerals and salts which can accumulate over time and form solid deposits known as evaporites. Some common examples of evaporites include rock salt, gypsum, and potash.

Option 2, a meteorite, is not the correct answer as meteorites are extraterrestrial objects that fall to Earth from space and are not related to the formation of evaporites.

Option 3, a brackish water pan, is also not the correct answer. A brackish water pan refers to a shallow body of brackish or saline water, but it is not the same as the rock formations known as evaporites.

Option 4, an evaporimeter, is not the correct answer either. An evaporimeter is a device used to measure the rate of evaporation of water, and it is not related to the formation or definition of evaporites.

In conclusion, evaporites are rocks that are formed through the evaporation of water, leaving behind dissolved minerals and salts. They are not meteorites, brackish water pans, or evaporimeters.