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_5, if x_5 drinks water, then x_5 is sad. For all x_5, x_5 will drink water. For all x_5, x_5 will write a letter and x_5 will play squash.
For all x_5, x_5 is sad can be inferred via the universal modus ponens rule. For all x_5, x_5 will write a letter can be inferred via the universal simplification rule. For all x_5, x_5 will play squash can be inferred via the universal simplification rule.