The intrusive feature formed when magma is injected into fractures cutting across preexisting rock layers is called a dike.

Here's why:

* Dikes are tabular, discordant (cutting across layers) intrusions of igneous rock. They form when magma is forced into existing fractures, often due to pressure from a larger magma chamber.

* Sills are also tabular intrusions, but they are concordant, meaning they run parallel to the existing rock layers.

* Laccoliths are dome-shaped intrusions that form when magma pushes upwards, creating a bulge in the overlying rock layers.

* Batholiths are massive, irregularly shaped intrusions that cover large areas and often form the core of mountain ranges.

Therefore, the correct answer is dike.