Directions: Read the passage and then choose the best answer to the question. Answer the question on the basis of what is stated or implied in the passage.
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:
Choice (D) is correct. The main idea of the passage is that underwater volcanoes receive little attention but can be dangerous. The author explains that while “people generally do not take note” of underwater eruptions because “the lava and smoke . . . is contained by the ocean,” such eruptions are dangerous because they are “capable of creating huge tidal waves, threatening coastal communities.” Choice (A) is incorrect because the passage highlights differences, not similarities, between traditional and underwater volcanoes. Choice (B) is incorrect because although the passage notes that the lava and smoke from underwater volcanoes is contained by the sea, that fact is not the main idea; it supports the larger point about what people notice. Choice (C) is incorrect because the passage does not indicate that most tidal waves are caused by underwater eruptions..