To determine the author's purpose in the paragraph, it's essential to analyze the specific content of the paragraph itself. However, based on the given responses, the author seems to be emphasizing the advantages of using real microscopes over smartphone microscopes, particularly regarding video capabilities.
The most fitting purpose appears to be:
to explain that real microscopes have video capability superior to smartphone microscopes.
This suggests a clear focus on the technical differences and advantages of traditional microscopes. If the paragraph includes comparisons of functionalities or focuses on the quality of video provided by each type, this response would be the most accurate.