When a king abdicates,
a) he seizes power
b)he leaves the throne
c)he makes new laws
d)he rules the nation

B)he leaves the throne

Historically this dates back firs with the Romans, then when Kingdoms were established monarchs giving up power. The abdication normally is an act of prudence since the king sees he is no longer in means to continue in power and seeks a pacific transition or wants to secure his life and that of his family. Another case mentioned below in recent years comes as a result of health issues that prevent the Royals, in turn, to continue in power.

An abdication is a mere act of a ruler that formally and legally passes the charge to another person. Many other reasons could be considerated

Some recent examples of this in modern history are to be mentioned:

-In Europe Netherlands, Belgium, Luxembourg, the Vatican City state health was the cause.

-In some rare cases but more frequently that one would expect, like the Netherlands, the last three monarchs have abdicated in order to pass the power to their breed.

-In Spain, King Juan Carlos announced his intent to abdicate in favor of his son as well.

under god i have placed my chiest strentgh and the safe guard to my loyal subjects