Question

(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. There is no single topic sentence.
B. There are no supporting details for the main idea.
C. The topic sentence is the found in the last line.
D. The author uses comparison and contrast to organize ideas.

Answer 1

You accidentally chopped off the end of answer choice D, but I'm assuming it said Sentence 7
Therefore, I would say that D is the correct answer.
Sentences 4, 5, and 6 (choices A, B, and C) all flow well with the previous sentences in the paragraph - sentence 4 continue's the talk about magma, and sentences 5 and 6 begin with continuations on a topic along the same lines - while sentence 7 introduces a new topic, plates colliding, without any transition word at the beginning. In addition, if we read the sentences in our head, sentence 7 sounds the most like an introductory sentence of a paragraph.
For all of these reasons, we can infer that sentence 7, choice D (hopefully), would be the best sentence for the beginning of a new paragraph