In which of the following the inheritance takes place only by male :-

Options

A. Nuclear
B. Cytoplasmic
C. co-dominance
D. Holandric inheritance

Answer

To solve the question "In which of the following the inheritance takes place only by male," we need to analyze the given options: nuclear inheritance, cytoplasmic inheritance, co-dominance, and holandric inheritance.

### Step-by-Step Solution:

1. **Understand the Types of Inheritance:**
- **Nuclear Inheritance:** This refers to the inheritance of genes located on chromosomes within the nucleus. Both males and females can inherit nuclear genes.
- **Cytoplasmic Inheritance:** This involves the inheritance of genes located in the cytoplasm, such as those in mitochondria. Both males and females can also inherit cytoplasmic genes.
- **Co-dominance:** This is a genetic scenario where both alleles in a heterozygote are fully expressed. This type of inheritance can occur in both males and females.
- **Holandric Inheritance:** This specifically refers to the inheritance of genes located on the Y chromosome. Since only males possess a Y chromosome, these traits can only be passed from father to son.

2. **Identify the Correct Answer:**
- Since holandric inheritance involves genes on the Y chromosome, which only males possess, this type of inheritance occurs exclusively in males. Therefore, the correct answer to the question is **holandric inheritance**.

3. **Conclusion:**
- The inheritance that takes place only by males is **holandric inheritance**.