I think that all of the above statements are being made by someone who is in need of crash course of 9th class physics.
Simple formula of calculating displacement of an engine is {(pi)x(r)^2x(h)}x(no of cylinders)
where pi = 3.1428
r = radius of cylinder (bore)
h = height of cylinder (stroke)
By doing above calculation you will get the volume of single cylinder, then just multiply it with the number of cylinders an engine have then you will get the total displacement of an engine.
So either by increasing bore or stroke then end result will be increased diplacement.
I wonder how many of the folks here have cleared their SSC exams .