Answer:
c. selective toxicity takes advantage of structural and/or metabolic differences between host and pathogen
Explanation:
Selective toxicity is the mechanism by which antibiotics work. They cause damage to the pathogen but do not harm the host. Hence, they are selectively toxic in their mechanism. They can target both the structural or the metabolic differences between host and pathogen. Many antibiotics target unique sites in the pathogen's structure or the sites which might be present in host cells too but are not essential for the survival of the host. An example of structural difference being targeted by antibiotics is the enzymes which synthesis the bacterial cell wall so that the cell wall is disrupted. A metabolic difference being targeted would be the mechanism by which bacteria replicates so that host cell replication process is not hindered.
The answer would be A. Blood cell formation
Bones can be fossilized.
Since bones are part of the skeletal system, your answer is...
SKELETAL
