I believe that is called an Avenger, Hope it helped!
To steer her readers in the right direction to solve the crime, Agatha Christie repeats key words and similar words. She did this so that these words will be retained in the mind of a reader. If a person reads the word three times, it is already kept in one's own mind. She was popular for making mystery stories based on famous nursery rhymes and poetry.
Answer:
the letter m
Explanation:
<h3>once in a
<u> m</u>inute, twice in a
<u> m</u>o<u>m</u>ent, never in<em> a thousand years</em></h3>
The answer is B, Their research