The type of inheritance in which many traits of a character are spead across a gradient and the effect of each allele is additive, is

Options

A. codominance
B. monohybride out cross
C. polygenic inheritance
D. dihybrid test cross

Answer

### Step-by-Step Solution

1. **Understanding the Question**: The question asks for the type of inheritance where traits of a character are spread across a gradient and each allele has an additive effect.

2. **Identifying Key Terms**: The key terms here are "traits spread across a gradient" and "additive effect of alleles". This indicates that we are looking for a type of inheritance that does not have distinct categories but rather a range of phenotypes.

3. **Recalling Mendelian Genetics**: Mendel's work primarily focused on traits that had clear contrasting forms (e.g., tall vs. dwarf plants). This is known as discontinuous variation. However, many traits in nature do not fit this model.

4. **Understanding Continuous Traits**: Continuous traits are those that show a range of phenotypes rather than distinct categories. Examples include height, skin color, and weight. These traits are influenced by multiple genes.

5. **Defining Polygenic Inheritance**: Polygenic inheritance refers to the inheritance of traits that are controlled by multiple genes. Each gene contributes to the phenotype in an additive manner, leading to a continuous range of possible traits.

6. **Examples of Polygenic Traits**: A common example of polygenic inheritance is human skin color, which is influenced by multiple genes (often cited as three genes: A, B, and C). The combination of dominant and recessive alleles from these genes results in a spectrum of skin tones.

7. **Conclusion**: Based on the understanding of the question and the definitions provided, the correct answer is **Polygenic Inheritance**.

### Final Answer
The type of inheritance in which many traits of a character are spread across a gradient and the effect of each allele is additive is **Polygenic Inheritance**.