What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all y, if y drinks water, then y is not climbing a mountain. For all y, y will climb a mountain. For all y, y will write a letter if and only if y will drink water. For all y, y will write a letter if and only if y is happy.
For all y, y will not drink water. For all y, if y writes a letter, then y is drinking water. For all y, if y writes a letter, then y is happy. For all y, if y drinks water, then y is writing a letter. For all y, if y were happy, then y is writing a letter.