B . Locard’s principle of exchange.
The correct answer is option B, that is, a person with type O blood has two recessive genes.
An illustration of a trait determined by a single gene is blood type. Each human exhibits two copies of the gene for blood type on chromosome pair number 9. One of the copy is inherited from the father and the other one is inherited from the mother. An individual's blood type is determined by which allele he or she inherits from the parents.
In case of blood type O, O is a recessive allele. If an A or B is inherited along with the O gene, the A or B gene decides the blood type of an individual. An individual is considered to have type O only if that person inherits two O genes, that is, a person with type O blood exhibits two recessive genes.
The answer is A. Class, because the divisions get smaller and smaller as they go down. Class is before Order so the division would be bigger.
Valence electrons would be found in the outermost shell of atom models!
Hope this helps (:
C -Chemosynthesis and decomposition
