How do interest groups lobby the executive branch? a. by filing lawsuits b. by appearing at administrative hearings to offer information c. by offering political action committee (pac) contributions to agency heads d. by filing amicus curiae briefs e. by drafting and introducing bills?

I believe the answer is: C. by offering political action committee (pac) contributions to agency heads

The contribution that given to the PAC would consist of monetary aid that would help a certain candidate in p[aying the expenses from his/her campaign.
In return, the candidate gives the implication that he/she will pass the legislations that would benefit the interest groups.