You cannot safely take-off below Vmcg or Vmca with a failure of the critical engine. The crew can, though, retard the throttles and safely reject the takeoff, even if refusal speed is below Vmcg. If there is a gap between V1 and rotate and the takeoff is continued, and Vmcg is less than rotate, and Vmca is less than Vlo (liftoff speed), then you're in trouble

As for the test question, I was confused on the answer as well...something like a max 10 knots reduction. Not something I've ever seen or heard of before; we had a short discussion during the interview but I can't remember the company answer...just ask a lot of questions in the tech portion and the time will fly by.

Good Luck!