What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Name the inference rule being used: There is at least one x_2 for which x_2 is not a mechanic or x_2 will climb a mountain. For all x_2, if x_2 were an office clerk, then x_2 is a musician. For all x_2, x_2 is a mechanic or x_2 is an office clerk. For all x_2, if x_2 climbs a mountain, then x_2 is a musician.
There is at least one x_2 for which x_2 is an office clerk or x_2 will climb a mountain can be inferred via the existential resolution rule.