A. Board-trigger; spring/catch. Impacts at neck, or over eyes. May impact forward of eyes. 
B. Adhesive board. Signs of struggle: high percentage of body surface in contact, side of head in contact.
C. Bait-trigger; spring/catch. Zero impact.
Choose C; option A unavailable.
Efficiency: four nights, four mice. Now, I've got to say that the mice which visit the front and back yards here are larger than Yorkshire mice; they are not the same thing at all. In appearance nocturnal: very dark fur, small recessed eyes. Tail same length as body only. Body slim, head long and narrow, nose pointed.
Options - commonest are drowning, scalding, or release.
Ask.com: can a mouse find its way home? A blind mole rat can navigate by the earth's magnetic field. Two miles away, past a school and next to a stadium; grass, small trees, shrubs.
Four nights. How many mice? These all look the same: size, colour, shape. This morning's release calm, quiet. Routine.
