Why did I get to choose from three different ways to pay for the Superproject?

[Meeplelowda]

In my very first game of Anachrony at move #386 I bought the Superproject "Archive of the eras." The base cost of the project is 1 Neutronium, 2 Titanium, and 2 Gold. I used an engineer, so I expected to pay 1 Neutronium, 1 Titanium, and 2 Gold. But instead I was given three options:
1) 1 N, 1 T, 1 G
2) 1 N, 1 T, 2 G
3) 1 N, 2 G

I chose option 1), but I don't understand why 1) and 3) were even available.

[kingdedede745]

The space you went to gives an additional discount of 1 N, 1 T, or 1 G.

Starting in era 5, the research, recruit, and construct actions on the main board all become more powerful by offering a bonus on their space, but they are one time use.

[Meeplelowda]

The space you went to gives an additional discount of 1 N, 1 T, or 1 G.

Starting in era 5, the research, recruit, and construct actions on the main board all become more powerful by offering a bonus on their space, but they are one time use.

Thanks.

For anyone reading this is in the future with the same question, here's the part of the rules I overlooked:

The Collapsing Capital tiles provide stronger, “last ditch”
versions of the Capital Actions (Worker restrictions still
apply). In addition to taking the Capital Action, the player
also receives the bonus depicted on the tile. A detailed list
of these bonuses can be found in the Appendix.