An effective conclusion for an essay should use a "hook" to get the reader's attention.
o
introduce a new idea.
O use signal words like “in conclusion.”
o include a new perspective on the thesis.

use signal words like “in conclusion.”

Include signal words like "in conclusion" is the correct choice

Explanation:

A hook is used in an intro, introducing new ideas is for body paragraphs, and new perspectives on the thesis should also be included in body paragraphs.

Hope this helps!