In 1943, drug companies began mass-producing penicillin. at that time, it was a medical miracle and was used as a remedy for infected wounds, pneumonia, and other bacterial diseases. just four years later, however, it was no longer effective on the same diseases that it had previously been able to cure. what happened?

Some of the bacteria mutated to become resistant to penicillin.

b. to discover aspects of the natural world.

hopefully i .

the correct answer is option d.

an appositive is a noun, noun phrase or noun clause which follows another noun or noun phrase in order to describe it or name it another way. they are usually used between commas, brackets or dashes.

the example sentence with the correct use of commas is the following:

her uncle, the man over there in the red shirt, owns the hardware store in town.