I'll address the three options at a very high level, before passing this to Ms. Garrett for some greater detail.
In the smaller option, first, security is there, plus back-of-House functionality. The medium-size one, on top of security, adds the library program and the visitor experience. Then the largest, on top of these two key objectives, adds some greater core parliamentary space, larger committee rooms for the Senate, for example, as well as meeting space for the House of Commons.
I will ask Ms. Garrett to add some greater detail.