Which statement is true of all rocks? (1) Rocks contain organic material. (2) Rocks contain fossils. (3) Rocks are composed of minerals. (4) Rocks are formed in layers.

The correct answer is - (3) Rocks are composed of minerals.

All rocks, sedimentary, igneous, or metamorphic are composed of minerals. The rocks can be composed of only one mineral, or they can be composed from two or more minerals.

The igneous rocks tend to be the ones that are composed of only one mineral. The sedimentary rocks are usually composed of two or more minerals, though there are some that are only from one mineral. The metamorphic rocks are the ones that are always composed of two or more minerals as they are rocks that have undergone a structural change under high pressures and temperatures, and also very often merge with other types of rocks in the process.

Option (3)

Explanation:

Rocks are usually referred to as the aggregates of minerals. These minerals are naturally forming, having a specific chemical composition and are solid and inorganic in nature. These minerals are of different types and are formed under different conditions.

The igneous minerals are formed during the crystallization of magma under various factors such as pressure and temperature of magma, composition, and rate of cooling of magma.

The sedimentary minerals such as silicates and clay minerals form the fabric of the rocks, formed due to the compaction and lithification of sediments.

The metamorphic minerals are those that are directly derived from the previously existed minerals of igneous or sedimentary rocks. These minerals alter due to the increasing pressure and temperature condition and form metamorphic minerals. Metamorphic minerals are very high-grade minerals.

Thus, the correct answer is option (3).