Why are primaries open

 In open primaries,  voters may choose on election day which party primary they want to participate in. I think that's why we have  open primaries.

Explanation:

the third answer is correct (c).

the laws that regulate the financing of political campaigns seek to guarantee the smoothness of funding so that there is no abuse of electoral economic power and to avoid the capture of future politicians by the donors.

this is because donor agents have their private interests that are not necessarily the same interests of the society that elected politicians must defend.

thus, interest groups should seek their interests within the legality of lobbying practices that are regulated.