A library has 'a' copies of one book, 'b' copies of each of two book, 'c' copies of each of three books and single copy of 'd' book. The number of ways in which these books can be distribute is?

• (a + b + c + d)! / (a! b! c!)
• (a + 2b + 3c + d)! / {a! (b!)2 (c!)3}
• (a + 2b + 3c + d )! / (a! b! c!)
• None of these