The correct answer is (D) The system increases the time taken for completion of the issue process.
This is not an advantage — in fact, Book Building through NSE reduces the time taken for completion of the issue process.
The source passage explicitly lists the advantages of Book Building through NSE, which include nationwide bidding, fair/transparent method, and lower costs. It states the system reduces (not increases) the time taken. Options A, B, and C are directly listed as advantages in the passage, making D the odd one out.