Ans. (A). alleles.
The two or more than alternative forms, shown by a gene, are are known as alleles. For example, a plant gene that controls plant height shows two alternative forms or allele, one for small height (represented by 't') and one for long height (represented by 'T').
The alleles arise due to mutations in wild type trait and are found at the same region of a chromosome.
Thus, the correct answer is option (A).
