As a Defense Measure to Keep Invading Military Troops from Using

As a defense measure to keep invading military troops from using their railroads,Spain and Russia

A) built explosives into bridges and tunnels.
B) made drive controls in locomotives opposite to what they were in the rest of Europe.
C) developed widths between the rails (gauges) different from those of the rest of Europe.
D) All of the above
E) None of the above