Modal with horizontal tabs, each tab has different content size

I have a modal, which has horizontal tabs at the top of it. Below the tabs is the tab content. Each content has different height. Without properly handling it - the modal size will have to change, which means that the tab's vertical positioning will also be changed.

Which of the following would you do:

  1. Let the modal change it's size without any further handling, which means the tabs' vertical position will be changed. (Worse in my opinion)
  2. Let the modal change it's size, but force the tabs to keep their vertical position, and only expand to the bottom. This option means that the modal will not be centered properly at the whole screen.
  3. Give the modal a fixed height (maybe the average height of all tabs), and put a scrollbar on contents that exceed this fixed height. This way will reduce any "jumps" in the modal. In addition, make an attempt to reduce the height of contents that exceed, using expanders and etc. (Best in my opinion)

Any opinions/ideas? Thanks!