(の中)で~が一番~です => out of this group, [A] is best N5
中 => While (Lasting) N3
Continuous
途中で/途中に => on the way; in the middle of ~ N4
一緒に => together N5
中 => During the period (Term) N3
Time
一度に => all at once N3
を中心に => focused on; centered on~ N2
一通り => Basically, (get) over, done N2
Base, base
最中に => while; during; in the middle of ~ N3
一方だ => more and more; continue to ~ N2
途中 (は) => on the way; in the middle of ~ N3
Halfway
一応 => more or less; pretty much; roughly; tentatively ~ N2