Question

in the middle ages, alchemists tried to transmute base metals into gold. for example, the process—producing four chemical changes in a base metal—allegedly rendered a gold - producing substance called the philosopher’s stone. today, we know this to be nonsense. but in 2013, kazem kashefi and adam brown, from michigan state university, demonstrated that gold could be produced through a biochemical process. the two team members of c. metallidurans metabolizes the toxic chemical gold chloride. it creates a by - product 24 - karat gold. as they were testing whether c. metallidurans could produce gold, kashefi and brown also assessed the bacterium’s hardiness. c. metallidurans is capable of surviving in extreme chemical conditions. the professors isolated c. metallidurans in a bioreactor with increasing amounts of gold chloride. because no other sustenance was available, the bacterium was forced to metabolize the toxin to survive.

which choice makes the sentence most grammatically acceptable?

a no change

b c. metallidurans also received an assessment of its hardiness performed by kashefi and brown.

c the bacterium also had an assessment of its hardiness done by kashefi and brown.

d the bacterium also got its hardiness assessed by kashefi and brown.

Explanation:

The original sentence has a passive - voice construction issue. The correct subject for the action of "assessed" should be "Kashefi and Brown" as they are the ones performing the assessment. Option C correctly rephrases the sentence to show that Kashefi and Brown are the doers of the action.

Answer:

C. Kashefi and Brown.