Defection refers to the act of changing one`s political party affiliation. Option 1 states that defection occurs when a politician changes their party after winning an election. This can happen when an elected official decides to switch parties for personal or ideological reasons. It is important to note that defection can also occur before winning an election (option 2), after losing an election (option 3), or even before losing an election (option 4) if a candidate decides to switch parties during the campaign. However, the most common form of defection is when an elected official changes parties after winning an election (option 1).