Answer:
B). Take notes and summarize notes.
Step-by-step explanation:
An informative essay is exemplified as the scholastic written document/essay that is chiefly inclined towards informing or notifying the audience about a particular subject, process, or event. It aims to elaborate on a specific topic or idea with adequate details that demand the students to note down the key points and recapitulate in a brief form(summary) as it offers a quite comprehensive and detailed knowledge of the domain/subject matter which is being explained.
As per the question, the choice that would be most constructive to focus your attention would be 'taking notes and summarizing' as it would help memorize the key points of the information presented and jot down brief outlook of the entire speech that would help form an opinion or judgment at the end of the class. Thus, option B is the correct answer.