Context: Then , the grand finale rumble ( or bottom burp , as Ian refers to it ) , went echoing first through my chamber , then , seconds later , through hers . I put my hand to my mouth in a dramatic gesture of embarrassment . Isla did the same . I giggled .

Question: What might Ian mean when he calls something a " bottom burp . "
Options:
0. It is something that is or sounds like flatulence .
1. It is the sound a person makes when they are embarrassed and giggle .
2. A bottom burp is something that goes through pipes quickly .
3. It is a rumble of a car or some other large chambered vehicle .
Answer: 0