Question

the three classes of rocks are sedimentary, metamorphic, and igneous. how are rocks classified into one of these three groups?
a. according to the type of minerals present in the rock
b. according to the method of their formation
c. according to how many times they have been through the rock cycle
d. according to their position in the lithosphere

Explanation:

Sedimentary rocks form from sediment - deposition and lithification. Metamorphic rocks form from pre - existing rocks undergoing metamorphism due to heat and pressure. Igneous rocks form from the cooling and solidification of magma or lava. So, rocks are classified by their formation method.

Answer:

B. According to the method of their formation