The corresponding Existential Instantiation rule: for the existential quantifier is slightly more complicated. For any sentence a, variable v, and constant symbol k that does not appear elsewhere in the knowledge base.
A. True
B. False
I have been asked this question in quiz.
This intriguing question originated from Inference in First-Order Logic in chapter Knowledge and Reasoning of Artificial Intelligence
Right choice is A. True
The best explanation: Rule of existential instantiation.