Answer:
Kafka gives no indication as to what may have caused Gregor's transformation.
Explanation:
Although we can interpret what Gregor's transformation represents, we have no indication of what caused it, since the author left no factor expressed in the narrative, probably to stimulate our interpretation of Gregor's dehumanization in the midst of capitalism and the exploitation he went through. Gregor's family and himself, see transformation as a random occurrence, something of chance, as a disease.