Paul studies life longevity and considers retired individuals who sell their houses to move into a flat. He can show that elderly people who move into a flat live longer. Which, of the following statement, captures a form of post-contractual opportunism that could explain this outcome?

	The ones who move into flats have an innate, better understanding of the benefits such a move will generate.
	The flat requires less maintenance so they can spend more time looking after themselves.
	The flats that these elderly persons select are particularly well suited to their needs.
	The ones who move into flats are healthier and/or wealthier than those who stay in their houses.