Alleles represent
A. different forms of a gene
B. same loci on homologous chromosomes
C. two or more forms
D. none of these

Options

A. A,C,
B. B,C
C. D
D. A,B,C

Answer

To solve the question regarding alleles, we will analyze each of the provided options step by step.

### Step 1: Understand what alleles are
Alleles are different versions or forms of a gene that occupy the same position (locus) on homologous chromosomes.

### Step 2: Analyze the options
- **Option A: Different forms of a gene**
- This is correct because alleles are indeed different forms of a gene.

- **Option B: Same loci on homologous chromosomes**
- This is also correct because alleles are found at the same locus on homologous chromosomes.

- **Option C: Two or more forms**
- This is correct as well, as alleles can exist in two or more forms (e.g., in the case of blood types, there are three alleles: A, B, and O).

- **Option D: None of these**
- This option is incorrect because options A, B, and C are all valid statements regarding alleles.

### Step 3: Conclusion
Since options A, B, and C are all correct, the best representation of alleles includes all these aspects. Therefore, the answer to the question is that alleles represent different forms of a gene, are found at the same loci on homologous chromosomes, and can exist in two or more forms.

### Final Answer
The correct answer is: **A, B, and C are correct.**

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