Answer:
The best answer choice for the question: When magma hardens in a volcano´s pipe, the result will eventually be a landform called a:___, C: Volcanic neck.
Step-by-step explanation:
A volcanic neck, also known as a lava neck, or volcanic plug, is literally a formation that surges at the very top of an active volcano in which the top layer of the lava in the vent, within a volcanic pipe, hardens and solidifies, exactly like a plug. The problem with these plugs, or necks is that they retain the flow of lava, and of gases, from the active volcano, and as these build up the pressure inside, at some point, they may cause violent explosions.