Microfossils often present in petroleum producing formations are those of

Options

A. Radiolarians
B. Diatoms
C. Helizoans
D. Foraminiferans.

Answer

To solve the question about which microfossils are often present in petroleum-producing formations, we can follow these steps:

### Step 1: Understand the Question
The question asks about microfossils that are commonly found in formations that produce petroleum. We need to identify which of the given options is most relevant to petroleum exploration.

### Step 2: Analyze the Options
We have four options to consider:
1. Radiolarians
2. Diatoms
3. Helizoans
4. Foraminiferans

### Step 3: Evaluate Each Option
- **Radiolarians**: These are single-celled protists with intricate silica skeletons. While they are important in geological dating, they are not specifically linked to petroleum formations.

- **Diatoms**: These are also single-celled algae with silica cell walls. They are primarily used in studies related to water quality and are not directly associated with petroleum deposits.

- **Helizoans**: These are organisms that can be found in both freshwater and marine environments. They are not specifically known for their association with petroleum formations.

- **Foraminiferans**: These are a group of amoeboid protists characterized by their calcareous shells. They are widely recognized as important microfossils in petroleum exploration due to their abundance in sedimentary rock formations that contain oil.

### Step 4: Identify the Correct Answer
Based on the evaluation, the correct answer is **Foraminiferans**, as they are the microfossils commonly used in petroleum exploration.

### Final Answer
The microfossils often present in petroleum-producing formations are those of **Foraminiferans**.

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