The correct option is A True
Volcano is a vent in Earth's crust through which rock, lava, hot vapour and gases are ejected.
Volcano forms when magma rises up towards the Earth's surface. The liquid rock is collected in chambers called magma chambers. The pressure builds up due to the expanding steam and gases associated with magma. As the pressure reaches a peak within these chambers, magma finds its way through a vent. This results in volcanic eruption and the expulsion of the hot molten rock. This hot molten rock is known as lava.