In order to get a recessive phenotype, both parents genotype must contain at least one recessive allele, i.e. parents must be either be both heterozygous, or one heterozygous and the other homozygous recessive, or both homozygous recessive. (I.e. Tt+Tt, Tt+tt, or tt+tt)
In this particular case, since both parents have dominant phenotype, so they must be both heterozygous for Tall, or both Tt.
The purpose of the Open Door Policy was to collaborate with other nations to maintain a common price level for free trade in China. The Open Door policy started in 1899. The correct answer is B.
This would cause the overpopulation in the grassland preserve. There would be too many antelopes and zebras that they would have to compete for survival. The food resources would run out for both species and cause a competition among every animal.
