Why does Gandalf choose bilbo for this quest?Whos desicion is it for Bilbo to come along

Gandalf really gives no specific reason for why Bilbo was chosen. We know that Bilbo is an exceptional hobbit. He is not ordinary. Gandalf explained his choice in the following way;

"Of course there is a mark," said Gandalf. "I put it there myself. For very good reasons. You asked me to find the fourteenth man for your expedition, and I chose Mr. Baggins. Just let any one say I chose the wrong man or the wrong house and you can stop at thirteen and have all the bad luck you like, or go back to digging coal." He scrowled so angrily at Gloin that the dwarf huddled back in his chair; and when Bilbo tried to open his mouth to ask a question, he turned and frowned at him and stuck out his bushy eyebrows, till Bilbo shut his mouth tight with a snap. "That's right," said Gandalf. "Lets have no more argument. I have chosen Mr. Baggins and that ought to be enough for all of you. If I say that he is a Burglar, a Burglar he is. or will be when the time comes.