Final answer:
The conclusion paragraph should effectively restate the thesis, summarize the main points, and provide a strong closing to be considered effective.
Step-by-step explanation:
The effectiveness of a conclusion paragraph in an essay can be critically evaluated based on its ability to tie together the main points of the text, create a finality, and leave a lasting impression without introducing new ideas. When considering the options provided, it's clear that the conclusion's efficiency lies in its recap of the essay's main points to support the thesis statement. The best conclusion paragraph reiterates the thesis in a new way, summarizes the main points to remind the reader of the validity of the argument, and provides a strong, effective close to the paper.