The author uses pacing to create the following effect:
c. Bewilderment.
Instead of feeling terrified, the reader is completely disoriented by Gregor Samsa's condition. What causes it is the fact that, although the character has just realized he has turned into a vermin, he is still able to think and reflect upon the situation in a lucid way.
That was one of Franz Kafka's trademarks: the description of overwhelmingly bewildering events in a serene pace which was not only his, but also the character's, who was able to reason despite the absurdity of the events he was going through.