Sentence Correction (SC) | Re: Since the start of space age, more and more littering has occured in o

The sentence begins with"Since the start of space age. " This tells us that the problem has occurred at an indefinite time in the past, and may continue into the present and future. This requires us to use the present perfect tense (i.e., has occurred, have occurred, have become, etc. ).

Since we need the past perfect tense here, we can ELIMINATE C and E
C) orbits near Earthbecame littered more and more, often resulting from
E) therehad been littering more and more of orbits near
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