Which of the following is NOT a type of rock?

Granite is a type of rock, specifically an igneous rock formed from the cooling and solidification of magma. Sedimentary rock and metamorphic rock are well-established categories of rocks based on their formation processes: sedimentary rock forms from the accumulation of sediment, while metamorphic rock is created through the alteration of existing rocks due to heat and pressure.

In contrast, "thermal rock" is not recognized as a classification in geology. There is no formal category of rock called thermal rock; instead, rock classifications are typically based on their formation and composition, such as igneous, sedimentary, and metamorphic types. Thus, the identification of thermal rock as not being a type of rock is correct, as it does not correspond to any known geological classification.