(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 topic sentence is the found in the last line.
B. There is no single topic sentence.
C. There are no supporting details for the main idea.
D. The author uses comparison and contrast to organize ideas.
The answer is D. There is no single topic sentence within this piece of writing. A topic sentence is used to summarize what is going to be, or what has been written about, and there is no such sentence within this piece.
