When measuring cylinder ovality (out-of-roundness) with a dial bore gauge, what specific measurements must be compared?

1. Measurements taken at the very top of the bore compared to the bottom of the bore.
2. Measurements taken parallel to the crankshaft axis compared to measurements taken perpendicular (thrust direction) at the same height.
3. The diameter of the cylinder bore compared to the diameter of the piston skirt.
4. The thickness of the cylinder wall at the intake side compared to the exhaust side.