12. Which of the following is a sedimentary rock? (A) granite (B) marble (C) shale (D) slate

Sedimentary rocks are formed from the accumulation of sediments, such as sand, silt, or clay, which are compressed over time. These rocks often have visible layers and may contain fossils. Among the options provided, granite is an igneous rock, marble is a metamorphic rock formed from limestone, slate is also a metamorphic rock formed from shale, and shale is a sedimentary rock. Therefore, the correct answer is (C) shale.