In 9:3:3:1 dihybrid phenotypic ratio, the number of hybrid dominant of both traits is

• The phenomenon of transfer of genetic characters from parents to progeny is known as inheritance. 
• Mendel was a scientist who studied the genetic patterns in pea plants and gave three laws describing patterns of inheritance. 
• A dihybrid cross is a cross between two organisms in which two physical characters are being studied. 
• In case of a dihybrid cross which includes homozygous dominant and recessive parents, the first generation will be heterozygous dominant. 
• When this heterozygous generation is crossed with itself it gives the genotypic ratio of 9:3:3:1. 
• In this cross the resulting second generation will have four instances in which the alleles are present in an heterozygous form. 
• It means that one allele will be present in dominant form and the other will be present in recessive form.

Hence, the correct option is D.