a) the advantages a candidate who is running for re-election has over the candidate trying to unseat him or her
Explanation:
Incumbency effect can be defined as the advantages a candidate who is running for re-election has over the candidate trying to unseat him or her in a democratic election process.
Basically, it refers to the tendency (phenomenon) for public officials such as senators or house of representative members who are already holding power (office) to get re-elected over an opposition. This ultimately implies that, a candidate contesting with an incumbent candidate is automatically placed at a disadvantage to emerge as the winner election due to the power of incumbency (incumbency effect).
<em>Additionally, the incumbency effect is peculiar to democratic elections and most favorable or stronger for the house of representative members.</em>
