In 1959, doctors began using the powerful antibiotic methicillin to treat infections of staphylococcus aureus, but within two years, methicillin-resistant strains of s. aureus (mrsa) appeared. how did the resistant strains of s. aureus emerge? a) in response to treatment of staphylococcus aureus infections with methicillin, some bacteria began to synthesize cell walls using a protein that was not affected by methicillin. these bacteria survived the methicillin treatments and reproduced at higher rates than did other individuals. over time, these resistant individuals became increasingly common. b) in response to treatment of staphylococcus aureus infections with methicillin, bacterial populations gradually began to synthesize cell walls using a protein that was not affected by methicillin. c) staphylococcus aureus bacteria that were able to synthesize cell walls using a protein that was not affected by methicillin survived the methicillin treatments and reproduced at higher rates than did other individuals. over time, these resistant individuals became increasingly common.

The correct answer will be option-B

Explanation:

Staphylococcus aureus is a gram-positive, spherical and one of the first described pathogens by scientific communities.  The S. aureus is known to cause a number of infections to humans in homes and hospitals and is able to adapt to the environmental conditions.

When Methicillin antibiotic was given to treat the infections caused by the S. aureus, within two years they became resistant to methicillin. This adaptability is the result of the due to the incorporation of the mecA gene at specific sites in their chromosomes.

This gene coded for an alternative penicillin-binding protein which has low affinity for the methicillin including other antibiotics. This gene spread to the S. aureus population and the species became resistant to methicillin.

Thus, Option-B is the correct answer.

c is the correct answer hope this !

answer and explanation;

volcanic rocks are igneous rocks which form from lava, molten rock which has been thrust out of a volcano onto the surface of a rocky body such as an asteroid, planet, or dwarf planet.  

plutonic rocks are igneous rocks which form from subterranean chambers of molten rock or magma. plutonic rocks make up the base of continental crust as well as oceanic crust. their slow rate of formation causes them to be coarse grained since there is plenty of time for large crystals to form before the magma solidifies into rock.

the textural difference is that plutonic rocks are more coarse grained than volcanic rocks. plutonic rocks are coarse grained while volcanic are fine grained ; glassey or fragmental. since fine and coarse are adjectives the decision as to whether a rock is fine or coarse grained is generally made on the bases of whether or not the individual crystals can be seen in most if the rock.