Information:  - Rebbe or , is a Yiddish word derived from the Hebrew word "rabbi", which means "master, teacher, or mentor". Like the title "rabbi" it refers to teachers of Torah or leaders of Judaism.  - In Judaism, a rabbi is a teacher of Torah. This title derives from the Hebrew word ' , meaning "My Master" (irregular plural ' ), which is the way a student would address a master of Torah. The word "master" "" literally means "great one".  - Judaism (from , derived from Greek , originally from Hebrew , "Yehudah", "Judah"; in Hebrew: , "Yahadut", the distinctive characteristics of the Judean ethnos) encompasses the religion, philosophy, culture and way of life of the Jewish people. Judaism is an ancient monotheistic religion, with the Torah as its foundational text (part of the larger text known as the Tanakh or Hebrew Bible), and supplemental oral tradition represented by later texts such as the Midrash and the Talmud. Judaism is considered by religious Jews to be the expression of the covenantal relationship that God established with the Children of Israel. With between 14.5 and 17.4 million adherents worldwide, Judaism is the tenth-largest religion in the world.  - Yiddish (or , "yidish"/"idish", "Jewish", ; in older sources - "Yidish-Taitsh", Judaeo-German) is the historical language of the Ashkenazi Jews. It originated during the 9th century in Central Europe, providing the nascent Ashkenazi community with an extensive Germanic based vernacular fused with elements taken from Hebrew and Aramaic, as well as from Slavic languages and traces of Romance languages. Yiddish is written with a fully vocalized alphabet based on the Hebrew script.  - Menachem Mendel Morgensztern of Kotzk , better known as the Kotzker Rebbe ( 1787 -- 1859 ) was a Hasidic rabbi and leader .    Given the paragraphs above, decide what entity has the relation 'ethnic group' with 'ashkenazi jews'.
A:
menachem mendel of kotzk