In the following passage some of the words have been left out. Read the passage carefully and select the correct answer for the given blank out of the four alternatives.

Books are our __ (1)____ friends. They are our guides. We can learn everything from them. The books contain all the great ___(2)___ of the world's leaders and we can learn them by reading the books. The books help us find ___(3)___ to our questions. The books never fail us. We should read as ___(4)___ books as we can. But all books are not good. So we should ___(5)___ only good books.