Among the following sedimentary rocks, which one is of organic origin ?

Options

A. Gypsum
B. Limestone
C. Nitre
D. Rock salt

Explanation

To determine which sedimentary rock among the given options is of organic origin, we can follow these steps:

### Step 1: Understand Sedimentary Rocks
Sedimentary rocks are formed from the accumulation and compaction of sediments. These sediments can be derived from various sources, including mineral fragments, organic materials, and chemical precipitates.

**Hint:** Remember that sedimentary rocks can be classified into three main types: clastic, chemical, and organic.

### Step 2: Identify Organic Sedimentary Rocks
Organic sedimentary rocks are formed from the accumulation of plant or animal debris. Common examples include coal (formed from plant material) and limestone (which can be formed from the accumulation of shells and coral).

**Hint:** Look for rocks that are formed from biological processes or contain significant amounts of organic material.

### Step 3: Analyze the Given Options
If the options provided include rocks like limestone, coal, sandstone, or shale, we can identify which one is of organic origin.

- **Limestone**: Can be organic if formed from shells or coral.
- **Coal**: Formed from the accumulation of plant material, thus it is organic.
- **Sandstone**: Typically clastic, made from sand grains.
- **Shale**: Usually formed from mud and clay, primarily clastic.

**Hint:** Focus on the rocks that are directly related to biological processes or contain organic material.

### Step 4: Conclusion
Among the options, coal is the most recognized organic sedimentary rock, as it is formed from the remains of plants that have undergone geological processes over millions of years.

**Final Answer:** Coal is the sedimentary rock of organic origin.