If the house and the senate pass different versions of a piece of legislation, the differences will be resolved BY A CONFERENCE COMMITTEE.
Conference committee is the committee of the United State congress which is appointed by the house of representative and senate to resolve disagreement on a particular bill. The committee is usually made up of the senior members of both house of representative and senate who originally considered the legislation.
Usually, back then, they followed their food and tracked them without settling too long in one place. But since that's not one of the answers I would go with A.
I hope that helps.
