One way the federal government supported domestic businesses in the late 1800s was by OA building a national road system.
OB. creating a national stock market.
OC. enacting strict labor regulations.
OD. increasing tariffs on foreign imports.

d

Explanation:

i believe that the answer to the question provided above is that the role of campaign committees is to act as a bridge between state and local campaigns.

d. i assume the underlined word is "role." reformat if it isn't.

explanation:

role is closest to part because when replacing words, "playing a vital decision," "playing a vital activity," and "playing a vital dollar" don't make logical sense. the only meaningful choice is "playing a vital part."

this fits one of merriam-webster's definitions of role: "a function or part performed especially in a particular operation or process."