This text describes a problem scientists are trying to solve. This text can be best described as

The correct answer is D an informational text.

An informational text aims to provide facts, explanations, or descriptions about a particular topic, which aligns with the description of scientists trying to solve a problem. This type of text is focused on conveying information rather than telling a story or expressing personal opinions. If you have more questions or need further clarification, feel free to ask!