In these question, a sentence/a part of the sentence is in bracket. Below are given alternatives to the in Bracket part at (a), (b), (c) which may improve the sentence. Choose the correct alternative. In case no improvement is needed your answer is (d)Question:(unless they modify the system.), our future generations will suffer:

• A. Unless the system is modified.
• B. Unless the system will be modified
• C. If the system will not be modified
• D. No improvement