Answer:
C. Joining an interest group
Step-by-step explanation:
Given the options available, the correct answer is Option C Joining an interest group, this is because, an interest group is a group whose purpose is to influence public opinion on political matters, using various forms of advocacy. For example, Human Rights for Education Committee, National Organization for Children Welfare, etc
It is not option A Reading unbiased media, because reading an unbiased media, will have little or no impact on the political difference.
It is not Option B. Writing a letter to the editor about a local business, because writing letter to editor on local business will not influence political matters, but only business related issues.
It is not option D. Serving in the military, because serving in military means, an individual have to follow orders of the superiors regardless whether it aligns with one political thought or not, otherwise, one will be charged for treason or insubordination.