Answer:
The correct answer is organic sedimentary rocks.
Step-by-step explanation:
Sedimentary rocks are the type of rock formed by the deposition of the smaller sediments due to wind, gravity and other natural factors.
The sedimentary rocks are divided into three types on the basis of their sediment material: chemical sedimentary rocks, clastic sedimentary rocks and organic sedimentary rocks.
Coal is formed by the accumulation of dead and decayed parts of plants and animals which is why they are called organic sedimentary rocks which takes millions of years to form.
Thus, organic sedimentary rocks are the correct answer.