(1) Earth's crust is made up of relatively rigid plates that ride atop Earth's hot, semiliquid mantle. (2) The plates are called
tectonic because they're in constant motion. (3) They can move because Earth's mantle is a very hot and semiliquid fluid called magma. (4) Volcanoes are a result of magma rising up or erupting through a plate, particularly where plate boundaries are moving against each other. (5) Also, when plates slide against each other, causing friction along adjacent plate boundaries, earthquakes frequently occur. (6) Therefore, we often find volcanoes and earthquakes along plate boundaries. (7) Plates may also collide. (8) When that happens, mountain ranges are formed. (9) For example, the collision of the plate carrying the Indian subcontinent created the Himalayan Mountains when it collided with the Asian plate. Which statement about this paragraph is accurate?
A. The author uses comparison and contrast to organize ideas.
B. The topic sentence is the found in the last line.
C. There are no supporting details for the main idea.
D. There is no single topic sentence.
The correct answer is D. There is no single topic sentence.
Explanation:
A topic sentence is a sentence that summarizes the main idea of a paragraph, this sentence is usually the first sentence in the paragraph and states what the paragraph is about. On the other hand, the paragraph presented here deals with multiple topics or concepts including the Earth's crust, the plates, the Earth's mantle, volcanoes, earthquakes, and mountain ranges, this means the paragraph is related to geography but explores multiple ideas that are not summarized in any of the sentences presented in the paragraph, neither at the beginning nor at the end of it. Thus, as there is no any sentence or phrase that states what the paragraph is about as a unit or summarizes all the ideas of the paragraph there is no a single topic sentence because this paragraph includes multiples ideas that might be difficult to summarize in only one topic sentence.
