Volcanoes may be scary, but they are the result of simple and very natural processes.
Explanation:
The options you were given are the following:
Volcanoes may be scary, but they are the result of simple and very natural processes.
"You can think of a volcano as a paper cut or a pimple on the Earth,"
Sometimes these eruptions can be small and ongoing, such as the Mt. Kilauea eruption in Hawaii that has been occurring since 1983.
When the lava and ash emitted from a volcano cool and harden, they gradually form mountains.
The topic sentence is the most important sentence of a paragraph. It's usually its first sentence, and it summarizes the information it contains.
The sentence that fulfills the given criteria is the first sentence: <em>Volcanoes may be scary, but they are the result of simple and very natural processes. </em>The paragraph tells us about volcanoes, about what they are and their significance. The first sentence summarizes this information well, unlike the rest of the options, which contain details.
