. Many Jews came to America to escape in Russia.

. pogroms

The Russian word pogrom refers to a massive violent attack on people with simultaneous destruction of their environment (homes, businesses, religious centers). Historically the term has been used to denote massive acts of violence, either spontaneous or premeditated, against Jews and other ethnic minorities living in Europe.

The word became internationally known after a wave of anti-Jewish riots swept southern Russia in 1881–1884, causing world-wide outcry and propelling mass Jewish emigration. According to the records of the history of the Jews in the United States, the Jewish emigration from Russia increased drastically in these years, totalling to about 2 million Russian Jews in period 1880–1920.

At least some of the pogroms are believed to have been organized or supported by the Tsarist Russian secret police, the Okhranka. Although no hard evidence has been presented so far, such facts as the indifference of Russian police and army were duly noted, e.g., during the three-day First Kishinev pogrom of 1903, as well as the preceding inciting anti-Jewish articles in newspapers, a hint that pogroms were in line with the internal policy of Imperial Russia. The most violently anti-Semitic movement during this period was the Black Hundred, which actively participated in the pogroms.

Many pogroms accompanied the Russian Revolution of 1917 and the following Russian Civil War. On one hand, wealthy Jews shared the fate of other wealthy people of Russia. On the other hand, Jewish settlements have undergone pogroms by the White Army, who acted in the accord with their "Jewish-Bolshevik plot" view of the Russian Revolution, derived from active Jewish participation in Bolshevik movement.

The organization of Jewish self-defence stopped the pogromists in certain areas during the second Kishinev pogrom.

Explanation:

answer is pogrom

the answer is option a.