When we think of volcanoes, eruptions, lava, and smoke-filled air come to mind-all occurring on land. Most people are surprised to learn about the prevalence of underwater volcanoes on our planet. Because the lava and smoke spilling out of an active, underwater volcano is
contained by the ocean, people generally do not take note of these eruptions. However, the largest underwater volcanoes are capable of
creating huge tidal waves, threatening coastal communities. The main idea of the passage is that

A: traditional volcanoes and underwater volcanoes
are similar

B: the lava and smoke from an underwater volcano is
contained by the sea

C: most tidal waves are caused by underwater
volcanoes

D: underwater volcanoes receive little attention but
can be dangerous