RITSUKO:“Yes, there is one child whose core
can be prepared immediately.”
UrsusArctos: Plot conveniences aside, it does raise the question of why there weren't other candidates for whom cores could be prepared at once.
Dr. Nick: There's a bit of a missed horror opportunity that we're never shown Nerv's core warehouse of fridged mommies. Ritsuko's line here would make more sense if Nerv was showing ethical restraint and keeping the cores unstuffed until the last moment, at which point they would need to stage an unfortunate accident to seemingly kill off a select mother of a Class 2-A kid.