What exactly was the choice Lyra was prophesied to make?

Question

In the His Dark Materials trilogy, the last book spends much of its time going on about the prophesy that Mrs Coulter overheard the witch talking about, regarding the choice Lyra was going to have to make, which was going to be like the choice Eve had to make in the Garden of Eden.

But the book never appears to state what this choice this was, unless I missed something really obvious. It mentions who the tempter is, but again that person never specifically asks Lyra to make a choice in doing something that I would consider to have had significant ramifications on all the worlds / heaven.

So can someone clarify exactly what the choice was she was destined to make?

Answer 1

The choice to leave childhood behind, and lose her "innocence". Expressed by her acting on her attraction and love for Will, and initiating their adult relationship.

Answer 2

At the end of the book she (and Will) have the option to stay together and use the Knife to open portals to each other to follow their love, but they decide not to and don't act on their desires.

Edit:

Back up by wikipedia:

In the first novel of His Dark Materials, Northern Lights (known in the United States of America as The Golden Compass), Serafina Pekkala tells of the prophecy of a girl who is "destined to bring about the end of destiny" at the expense of a great betrayal. It transpires that Lyra's destiny is to be the second Eve and fall into the temptation of the serpent, represented by Mary Malone....However, in order to ensure the stability of the universes and protect people from the creation of Spectres, Will and Lyra must close all of the inter-dimensional windows with the help of angels and keep them closed forever - and since their dæmons cannot live outside of their own birth worlds, they must part forever.