Not to take away from DY’s post.
Hatzalah guys wear a radio, and go to shul, and daven, and go home, and eat a seudah (and yell at their kids and swill scotch and fall asleep on couch). Albeit perhaps also run out on a few calls.
Doctors put on their work clothes, go to their regular job. While their kids sit at home and mother yells at them.
I posit that choice A is shabbos, and choice B is not.
Accountants keep shabbos. Lawyers keep shabbos. Mechanics keep shabbos. Laundry chute sweepers keep shabbos. Elephant trainers keep shabbos. All jobs that are 7 days a week you can keep shabbos and you just don’t do the shabbos shift. Except doctors don’t keep shabbos.