Discarding Energies

[unknown]

I know that you cannot discard extra energies but how about in this situation.

Salamance EX has the following attached: water, fire, boost.

The attack calls to discard 2 energies.

Can I discard a fire and the boost?

I think that you can, but want to be sure.


edit to answer pokepop's question

But why not just discard the Boost?

to lessen the amount of energies in the field, against a gardy.

 

[PokePop]

Sure, you can if you want to, if you choose the Fire first.
But why not just discard the Boost? That fills the requirement all by itself.