Metamagic spells and concentration checks

[Happler]

I was just reading something and I think that I may be missing it.

If you are trying to cast a quickened fireball defensibly, what would be the DC?

Would it be:

a) 15+(3*2) = 21 (as it was a 3rd level spell)

or

b) 15+(7*2) = 29 (as if it was a 7th level spell (the slot that it is now using).

TL/DR: Do Metamagic feats effect the Spell level for concentration checks?

[concerro]

Metamagic feats don't change the spell level, only the level of the spell slot so unless you use heighten spell the DC for concentration will not change.

[Happler]

concerro wrote:

Metamagic feats don't change the spell level, only the level of the spell slot so unless you use heighten spell the DC for concentration will not change.

that is what I thought, but I was not 100% sure. Thanks.