The correct answer is C. Abdication : Throne.
A resignation is the act of giving up one’s position or office. An abdication is the act of giving up one’s throne or position as monarch. In both cases, the person is voluntarily giving up their position of power.
A competition is a contest between two or more people or groups to see who is the best or who can do something the best. A game is a form of amusement or entertainment that is usually competitive and has rules. In both cases, the participants are trying to win.
Illness is a state of being unhealthy or unwell. A hospital is a place where people who are ill or injured are treated. In both cases, the people involved are not feeling well.
Moisture is the presence of water or another liquid in the air or on a surface. Rain is water that falls from the sky in drops. In both cases, there is water present.
However, the relationship between resignation and office is more similar to the relationship between abdication and throne than it is to the relationships between competition and game, illness and hospital, or moisture and rain. This is because resignation and abdication are both acts of giving up a position of power, while competition and game, illness and hospital, and moisture and rain are not.