The word Kafkaesque refers to something marked by illogical, terrifying, and disorienting complexity. Which of the following aspects of Franz Kafka's The Metamorphosis relate to this term?

I would say that these aspects of Franz Kafka's The Metamorphosis relate to the term Kafkaesque: the dystopian world that Gregor enters as an insect, and Gregor's sudden transformation into a giant insect.

I believe the answer is: the dystopian world that Gregor enters as an insect, and Gregor's sudden transformation into a giant insect.

Something would be marked by illogical, terrifying, and disorienting complexity if that thing couldn't be accomplished with scientific method in any form.

The fact that a person could transform into insects pretty much tell that the world that become the sting of the writing is a dystopian or imaginative world.