Lava is
a. always produced during any volcanic activity.
b. molten rock that cools and hardens on earth's surface.
c. the most life-threatening volcanic product of any eruption.
d. all the same chemical composition, whether it is rhyolite or basalt

molten rock that cools and hardens on Earth's surface.

Explanation: Lava is liquid rock that are thrown to the Earth's surface by the action of a volcanic eruption. On cooling a Lava form an igneous rock. The Lava are found in the Earth's crust naturally but are thrown to the surface during a volcanic eruption. Lava has the ability to travel long distances during an Eruption.