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: If it is sunny, then David is a soldier. For all x_17, if x_17 were a soldier, then x_17 is a mechanic. If David were a mechanic, then David is a soldier. David is not a mechanic. If it is cold, then it is sunny.
If it is cold, then David is a soldier can be inferred via the transitivity rule.