Answer:
External locus of control.
Explanation:
Attribution theory has two concepts that determine the attitude of a person towards an object or self.
The external locus of control: The external locus of control deals when a person blames or give all credit for their failure or success to the external source. It means a person believe in fate, luck, situation, etc. It is opposite to the internal locus of control.
Thus Della is on an external locus of control where she believes in lucky guesses. She believes in fate, luck that is an external source.