It's #3 because of the Quartering Acts; relating to a very specific set of facts during the Revolutionary War. Consider for a moment that if General Gage hadn't persuaded the British Parliament of the need to amend the Mutiny Act to require American towns to provide food and shelter to British troops, then this amendment would never have been passed.

It was passed because of what was top-of-mind for the writers in the 1780s. It's dead letter. There has been one case on it in 200 years.

  s/dead letter/stable and working as intended/

Yep, the context is interesting. Hopefully we'll never see quartering again but as the saying goes: history rhymes.