What is one way political parties shape public policy?

a. monitoring elections and administering ballots.

b. building public support for party candidates and positions.

c. nominating candidates for important cabinet positions.

d. holding national conventions.

B Building public support for party candidates and positions.

Explanation:

Political parties shape public policies by building support for party's candidates and positions. Candidates of any political parties are face of that party and party can win election through them so it is responsibility of party to choose right candidates  whose all records are clean and build support for them. And by building public policies they provide a stand and support to their candidates.

a is correct

hope this let me know if it is right

the answer is b. hope this