Answer:b
Step-by-step explanation:
In the sentence the verbs are correct because-
When since demonstrates an action from the point of time in the past, we can use the past simple or present perfect after since.The main clause is also correct.
Transitional words and punctuations are also correct.
But the writting flow of the sentence is hindered due to using too many words to show the intensity of their working instead of a single but effective word.Though the sentence seems correct but in english only grammatical structure can't determine the accuracy of a sentence;style,tone should also be considered.
A cliché is a tired phrase that, because of overuse, loses its impact. Using it sometimes make the sentence dull.
So the answer is b