The basic cause of variations is

Options

A. Mutations
B. Out crossing
C. Incrossing
D. Recombinations

Answer

### Step-by-Step Solution:

1. **Understanding Variations**: Variations refer to the differences in the genetic makeup among individuals within a population. These differences can manifest in physical traits, behaviors, and other characteristics.

2. **Identifying Causes of Variations**: The question asks for the basic cause of variations. There are several processes that can lead to variations, including mutations, outcrossing, inbreeding (in crossing), and recombinations.

3. **Defining Mutations**: Mutations are changes in the DNA sequence of an organism's genome. They can occur due to various factors such as environmental influences, errors during DNA replication, or can be inherited.

4. **Role of Mutations in Variation**: Mutations are considered the primary source of genetic variation. A single mutation can have significant effects on an organism, and over time, the accumulation of multiple mutations can lead to evolutionary changes within a population.

5. **Evaluating Other Options**:
- **Outcrossing**: This refers to the breeding of unrelated individuals and can introduce new genetic material but is not a direct cause of genetic variation.
- **Inbreeding (In Crossing)**: This involves breeding between closely related individuals, which can reduce genetic diversity rather than create it.
- **Recombinations**: These occur during the process of meiosis when chromosomes exchange genetic material, but they are not the fundamental cause of new variations.

6. **Conclusion**: Based on the definitions and roles of these processes, the basic cause of variations is identified as mutations.

### Final Answer:
The basic cause of variations is **mutations**.

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