Question

how can a scientist predict how explosive the eruption of a volcano will likely be?
by studying the composition of its volcanic rock
by determining if the volcano is active, dormant, or extinct
by using a cospec to check the gases
by using a tiltmeter to check the ground swelling

Explanation:

To predict a volcano's eruption explosiveness, studying volcanic rock composition (like silica content) is key. Silica affects gas retention and eruption style. Determining activity status (active/dormant/extinct) doesn't predict explosiveness. COSPEC measures sulfur dioxide (for gas output, not explosiveness directly). A tiltmeter measures ground deformation (for eruption timing, not explosiveness). So the correct method is studying volcanic rock composition.

Answer:

A. by studying the composition of its volcanic rock