The primary election, in which voters choose the presidential nominees, was introduced during the Jacksonian era. is used in Europe as well as in the United States. became the primary model for selecting party presidential nominees in the later half of the 20thcentury. is designed to strengthen the political parties. was introduced during the Cleveland era.

The primary election, in which voters choose the presidential nominees became the primary model for selecting party presidential nominees in the later half of the 20th century.

Explanation:

The primary election, also generally known as the primaries, is a process in which voters choose or indicate who they prefer to be their candidate(s) in an election. This election is usually done to select the candidates for the major or main election(s).

This form of selection that helped voters determine their preferred candidates is done to choose the presidential nominees. This process later became the primary model for selecting the presidential nominee, especially in recent years.

Thus, the correct answer is the third option.

i think its either b or c

explanation: