Read Each of the Following Essay Introductions

Read each of the following essay introductions. Then select the letter of the method the writer used to begin the composition. The essay below begins with a(n)
One day in 1946, Percy Spencer stuck a chocolate bar in his pocket and went to work. Later, standing next to the radar machine he was working on, he noticed that his chocolate bar had melted. Almost immediately, Spencer saw the possibilities, sent for unpopped popcorn, and invented the first microwave oven ⎯ marketed the following year as the "radar range." The microwave is just one of many important inventions created out of the interaction of two factors: a lucky accident and the presence of a trained person who understood what that accident meant.

A) single-sentence thesis statement.
B) contradiction.
C) illustration.