Final answer:
After anti-immigration legislation like the Chinese Exclusion Act curtailed Asian immigration to the U.S., this led to increased immigration from other regions, such as Mexico, to fill the labor vacuum created.
Step-by-step explanation:
When anti-immigration legislation stopped Asian workers from coming to America, particularly due to the Chinese Exclusion Act of 1882 and subsequent laws which extended these restrictions to other Asian populations, several social and economic shifts occurred. The exclusionary policies led to a decrease in the availability of low-cost labor particularly in industries like railroads, agriculture, and mining where Asian immigrants had previously been a significant workforce. This policy vacuum opened labor opportunities which were then sometimes filled by other immigrant groups, including those from Mexico. As such, the correct answer is that Mexican immigration increased (option a).
It is important to recognize that these anti-immigration laws were largely a product of economic fears among existing citizens, often stoked by racism and the belief that these immigrant groups would take jobs from native-born Americans or were otherwise undesirable. Over the decades, these attitudes towards immigration policy changed, often tied to larger political and economic trends within the United States.