Irony is definitely the answer to your question.
The correct answer is A. To give instructions on how to make a pinhole viewer in order to see a solar eclipse.
Explanation
According to the previous text, it can be affirmed that the text has the objective of giving instructions on how to make a hole viewer to see a solar eclipse because the author uses a structure in which he takes sequential steps to elaborate a solar viewer. For example, the author gives four steps to make the viewer using two cardboards and pinhole. So, the correct answer is A. To give instructions on how to make a pinhole viewer in order to see a solar eclipse.
