Widespread gerrymandering can affect both state and national policy by:
A. Increasing the number of laws passed each year due to greater cooperation by elected officials at each level.
B. Increasing voter turnout and making elected officials more accountable to the citizens of each state.
C. Increasing the chances of one party enacting its platform in state legislatures and the House of Representatives.
D. Increasing cooperation between state and national governments to pass and enforce similar laws.

Gerrymandering refers to the manipulation of electoral district boundaries to favor a particular political party or group. This practice can significantly influence both state and national policy, shaping legislative outcomes and affecting political power dynamics.

Explanation
When gerrymandering occurs, it often results in districts that are drawn in ways that benefit a specific political party, leading to unbalanced representation. This can have broad implications, especially at the state and national levels. One key effect of gerrymandering is that it increases the likelihood of one party controlling more seats in state legislatures and the U.S. House of Representatives, thereby enabling that party to pass legislation aligned with its platform. This effect can shape national policy, as the party with more influence in state legislatures and Congress can push its agenda forward more effectively.

Answer
The correct answer is:
C. Increasing the chances of one party enacting its platform in state legislatures and the House of Representatives.