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: For all x_10, x_10 is an office clerk or x_10 is sad. For all x_10, if x_10 were an office clerk, then x_10 is an electrician. For all x_10, if x_10 were an electrician, then x_10 is curious. There is at least one x_10 for which if x_10 were sad, then x_10 is curious.
For all x_10, if x_10 were an office clerk, then x_10 is curious can be inferred via the universal transitivity rule.