What was one of the positive effects of westward expansion?

a. people from different ethnicities and backgrounds worked together and developed good relations.

b. americans mingled with gauchos and vaqueros from argentina and mexico.

c. american indians taught the new immigrants how to survive in the new territories.

d. american cowboys created a new form of entertainment, the rodeo.

Option A, People from different ethnicities and backgrounds worked together and developed good relations

Explanation:

During the westward expansion in 19th century, the Native Americans tried to expand their foots in the lands of Native Americans. The white Americans were attracted towards the western land because of its land and gold.  

Some of the positive impacts are as follows –  

a)Immigrants gained better life and opportunities as immigrants learned to grew large crops and earned profits

b)Economic growth happened as farming, industrial, and manufacturing sectors intensified  

c)Government policies were favourable such as financing agricultural education, The Homestead Act etc

Hence, option A is correct

a system of cooperative federalism emerged, as the powers of the federal government expanded.