Number of dog spikes normally used per rail seat on curved track is A. one on either side B. two outside and one inside C. one outside and two inside D. two outside and two inside

The correct answer is: A. one on either side.

Dog spikes are used to secure the rails to the sleepers on curved track. They are placed one on either side of the rail, at the point where the rail meets the sleeper. This helps to prevent the rail from derailing as it travels around the curve.

Option B is incorrect because it would not provide enough support for the rail. Option C is incorrect because it would not provide enough support for the rail on the inside of the curve. Option D is incorrect because it would provide too much support for the rail, which could cause it to buckle.