Since the majority of customers are not complaining when

Hi ankurgupta03,

Since the majority of customers are not complaining when they are dissatisfied, even those organizations most concerned with customer service have only a single opportunity to establish brand loyalty.

A. Since the majority of customers are not complaining
B. Since the majority of customers have not complained
C. Since the majority of customers do not complain
D. When the majority of customers do not complain
E. In the event that the majority of customers are not complaining

Can somebody please explain the usage of since here

The verbs in A, B and E are incorrect, so that leaves us with a Since/When decision between C and D. For C, Since tells us that this is a reason for the rest of the sentence. Companies only have one chance at brand loyalty. Why? Because people don't complain when service is bad. This is perfect.

Contrast with choice D. Companies only have once chance at brand loyalty, but only when the majority of customers do not complain. They can have multiple chances in other contexts. This incorrectly modifies the entire meaning of the sentence, and shifts it from causality to an occasional preference. The answer here must be C.

Hope this helps!
-Ron