Which of the Following Is an Example of Issue Uptake

Which of the following is an example of issue uptake?

A) A challenger raises the issue of immigration during a campaign, and the incumbent later sponsors immigration reform.
B) Gun rights activists organize around defeating an assault ban and make independent expenditures in several congressional races.
C) A challenger runs negative campaign ads aimed at a single vote taken by a Senator on campaign finance.
D) A candidate identifies single-issue voters in her district and runs a campaign ad targeted at those voters.