The correct option is (a) 1 only.
Explanation
Fossils are the preserved remains, impressions, or traces of ancient organisms. Their presence is a defining characteristic used to distinguish between different types of rock formations based on their mode of origin.
- Statement 1 is Correct: Fossils are the remains of dead plants and animals that have been trapped and preserved in the layers of rocks over geological time scales. These remains undergo various processes such as petrification or carbonization to become part of the rock record.
- Statement 2 is Incorrect: Fossils are most commonly found in Sedimentary rocks (e.g., limestone, sandstone, shale). Sedimentary rocks are formed by the accumulation and lithification of sediments at relatively low temperatures, which allows organic remains to be preserved. In contrast, Igneous rocks form from the cooling and solidification of molten magma or lava at extremely high temperatures, which destroys any organic matter present.
Key Takeaway: Fossils are exclusive to Sedimentary rocks because the high heat involved in the formation of Igneous rocks and the heat/pressure involved in Metamorphic rocks generally destroy organic remains.