Which of the following is a good example of multiple allele-

Options

A. ABO blood groups
B. Size os starch grain in pea
C. Shape of seed
D. Flower colour in pea

Answer

### Step-by-Step Solution:

1. **Understanding Multiple Allelism**:
- Multiple allelism refers to a situation where a single gene has more than two alleles. This means that for a particular trait, there can be multiple variations (alleles) that influence the phenotype.

2. **Identifying Examples**:
- To identify a good example of multiple alleles, we need to look for traits that are controlled by more than two alleles. A classic example of this is the ABO blood group system.

3. **ABO Blood Group System**:
- The ABO blood group is determined by a single gene located on chromosome 9. This gene has three alleles:
- **I^A** (which codes for type A blood)
- **I^B** (which codes for type B blood)
- **i** (which codes for type O blood)
- The presence of these alleles can result in four possible blood types: A, B, AB, and O, showcasing the concept of multiple alleles.

4. **Comparing Other Traits**:
- Other traits mentioned, such as the size of starch grains in peas, shape of seeds, and flower color, are controlled by single genes with only two alleles (e.g., dominant and recessive). Therefore, they do not exemplify multiple allelism.

5. **Conclusion**:
- The best example of multiple allelism from the options provided is the ABO blood group system, as it involves more than two alleles influencing a single trait.

### Final Answer:
The ABO blood group system is a good example of multiple alleles.