Suppose a knowledge base contains just one sentence Ðx As High As (x, Everest). Which of the following arc legitimate results of applying Existential Instantiation?
a. As High As (Everest, Everest).
b. As High As (Kilimanjaro, Everest).
c. As High As (Kilimanjaro, Everest) ^ As High As (Ben Nevis Everest) (after two applications).