I would say the answer is b but all of the answer choices could be the correct answer(hope that helps)
        
             
        
        
        
The different DNA sequence for a gene shows that same character can be expressed in 2 or more forms. Alleles are present on homologous chromosome.
Explanation:
The gene is the DNA sequences on the chromosome coding for the particular trait in an organism.
The alleles are the variant of the gene. In a homologous chromosome the variant of the gene or allele is present. The homologous chromosome is present in progeny one from each parent. 
For example the allele for tall as homozygous is present on one of the parent and shortness on the other parent in homologous chromosome. The trait of height is the gene and the way it expresses itself is the trait from either parent. The DNA sequence will also be different for the alleles because they will code for different proteins like short or tall phenotype.
The genotype will be different hence DNA sequence is also changed.
 
        
             
        
        
        
Answer:
The main purpose of these therapies are to suppress the immune system and destroy cancer cells of the blood by destroying the ability of the body to produce blood cells inside the bone marrow in preparation of the bone marrow for the new stem cells from the donor.
Explanation:
In the treatment of acute myeloid leukemia (AML), hematopoietic stem cell transplantation (HSCT) procedure is employed. It involves the infusion of healthy blood-forming stem cells from a donor into the body of the patient to initiate production of healthy blood cells after the hematopoietic function of the bone marrow of the patient has been destroyed by chemotherapy and radiation.
Before the stem transplant, the patient is subjected to a conditioning process or therapy, which involves undergoing a treatment through chemotherapy and radiation therapy. <em>The main purpose of these therapies are to suppress the immune system and destroy cancer cells of the blood by destroying the ability of the body to produce blood cells inside the bone marrow in preparation of the bone marrow for the new stem cells from the donor.
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After these therapies, the transplant infusion takes place, which is usually painless.
 
        
             
        
        
        
Answer:
trophic level
Explanation:
The energy pyramid indicates how energy is transferred from one organism to the next on the food chain. There are four main levels, starting at the base with producers that take energy from the sun, and moving upward to primary, secondary and tertiary consumers. The pyramid of numbers represent the number of organism in each trophic level.