The correct option is D 1985
"Defection" is the act of leaving a political party to join another one. This defection was motivated by a number of reasons. Some members were convinced by a rival party that they’ll get a public post or greater power. Others were offered money. But the end result was chaos in the legislature.
To prevent this from happening in the future, an Anti-Defection Law was passed in 1985, and added to the Constitution’s Tenth Schedule.