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.

the following sets of characteristics describe what we know about the outer plants is c. rocky surface, closet to the sun and larger in size