99% of the time, I present concepts over email. I have several clients that I’ve never actually met face to face.
There is nothing you can do to prevent someone from skipping ahead in your PDF presentation. The best thing you can do is provide them with a strong enough presentation that provides context for each option you present.
I typically present each option on it’s own page/slide, along with a short description of what makes this option unique compared to the other options. Maybe even include alternate views of the option on the same page as well. And if its a very large/deep conceptual project, I might even provide title/transition pages between each options to provide more context to the option they are about to see.
Then I will follow up all of the options with a comparison page that shows each option together on one page.
And finally, a page dedicated to alternate designs that were made in the process of making the main options I presented.
In the email, I might say which one is my favorite and briefly state the reasons why.