The correct answer is A. all individuals having same phenotype.
A biotype is a group of individuals that have the same phenotype, or physical appearance. This can be due to the fact that they have the same genotype, or genetic makeup, or it can be due to environmental factors that have caused them to develop the same phenotype.
Option B is incorrect because it refers to the genotype, or genetic makeup, of individuals. The phenotype is the physical appearance of an individual, which is not necessarily determined by the genotype.
Option C is incorrect because it refers to individuals with different phenotypes. A biotype is a group of individuals with the same phenotype.
Option D is incorrect because it refers to individuals with different genotypes. A biotype is a group of individuals with the same phenotype.