A — Rock A is Extrusive Igneous rock. This is because it is located on the surface of the Earth, where lava has flowed out through fissure and solidified.
B — Rock B is a Dyke. This is because magma when forced upwards fills vertical cracks or fissures in existing rocks. It then hardens there to form dykes.
C — Rock C is a Sill. This is because magma flows between layers of rocks horizontally and then hardens there. This layer of intrusive rock is called Sill.