The earthquake spell is a bit unusual in that it calls for two saving throws:
[...] Each creature on the ground that is concentrating must make a Constitution saving throw. On a failed save, the creature's concentration is broken.
When you cast this spell and at the end of each turn you spend concentrating on it, each creature on the ground in the area must make a Dexterity saving throw. [...]
If the spell is cast and an affected creature is concentrating on a spell, they must make two saving throws. Meanwhile, the Careful Spell Metamagic states:
When you cast a spell that forces other creatures to make a saving throw, you can protect some of those creatures from the spell’s full force. To do so, you spend 1 sorcery point and choose a number of those creatures up to your Charisma modifier (minimum of one creature). A chosen creature automatically succeeds on its saving throw against the spell.
Which saving throw can the Sorcerer decide is automatically succeeds? Can they choose earthquake's specifically called for concentration saving throw?