Aform of government where political authority rests with a single leader autocratic or democratic

The correct answer is - autocratic.

The governments where the political authority rests with a single leader is called autocratic government. In this type of governments, the leaders have absolute power in the country, their word is law, and there isn't any institution that monitors or restricts them. In this type of governments there isn't multiple parties from which the people can choose on elections who should be their leader.

This system has largely been abandoned around the world. There isn't a single developed country that has a government like this, but there are some developing or less developed countries that unfortunately are in the hands of such governments.

Examples of such governments are Belarus, Turkmenistan, North Korea.