Explanation:

Correct answer is (c).If we read the two sentences they are connected by the cause and effect relationship where one is the reason and the other is the result of something. Among the given options, ‘as’ is the correct choice since it connects the sentences as cause and effect. Combining the two sentences the new sentence will be: As banks are left with no other option but to issue the old notes to their customers in the absence of fresh notes from the RBI, the notification by the Reserve Bank of India to do away with stapling off currency notes by banks has not done much difference.  So, Option C is the right choice among the given options